Non-system disk or disk error message

This type of message appears when the computer attempts to boot from a disk on which Windows is not installed, or if the disk is corrupted. Remove any removable media from the device, and disconnect any drive that's connected to the computer through a USB port. Press any key to continue startup. If that doesn't work, press Ctrl+Alt+Del or restart the computer with the main on/off switch.

Computer starts but mouse and keyboard don't work

If the computer starts but doesn't respond to the mouse and keyboard, turn off the computer. Unplug both the mouse and keyboard from the computer. For USB mice and keyboards, unplug each and re-connect them. Ensure each USB connection is tight and secure. If the plug is round and green, make sure you plug it into the PS/2 port for the mouse (usually colored green), but only when the PC is turned off. Make sure nothing is resting on the keyboard and holding down a key. Then firmly plug in the keyboard. If the plug is round and purple, plug it into the PS/2 port for the keyboard (only when the PC is turned off). Check all cable connections to the computer one more time. Then restart the computer.

Screen turns blue during startup and then stops

This is commonly referred to as the “blue screen of death.” It doesn't mean your computer is permanently broken. A frequent cause of this problem is a device driver for a hardware device that doesn't work with Windows 10. If you recently connected or installed a new hardware device, disconnect or uninstall it. Then start the computer again.

If you still see the blue screen, you'll very likely have to boot to Safe Mode and disable the device through Device Manager. Typically, the average user does not attempt this procedure — leave it to a professional. But if you want to take a shot at fixing this problem yourself, follow the instructions in this section and see Chapter 37.

If the error persists, look for an error number on the blue screen of death page. It most likely starts with the characters 0x. Jot down that number on a sheet of paper. Then, if you can get online through another computer, go to Microsoft's site (http://www.microsoft.com) or your favorite online search engine (such as Google or Bing) and search for that number. You might find a page that offers an exact solution to your problem.

If you can get online through another computer, consider posting a question at the Windows Communities site (http://answers.microsoft.com/en-us/windows). Be sure to include the error number in your post. You may find someone who has already experienced and solved that very problem.

Restore system files to an earlier time

The Windows 10 Advanced Startup options (described in the “Advanced Startup” section of this chapter) include a System Restore item that enables you to restore your system to a previous state if System Protection is turned on. Windows 10 creates restore points automatically, and you can create additional restore points using the Recovery item in the Control Panel. To recover your system to a previous state, boot using the Advanced Startup options as explained later in this chapter, and then choose System Restore from the Advanced Options screen. Follow the prompts to choose a restore point from which to restore.

Alternatively, if you can get the computer to start in Safe Mode, you can use System Restore to restore your PC. Boot to Safe Mode and then open the Control Panel. In the Restore item, click Open System Restore to choose a restore point and start the restore process.

Windows 10 Automatic Repair Mode

If Windows 10 automatically detects an issue with your startup, you see a light blue window (not the blue screen of death) that reads “Automatic Repair.” This is the Windows 10 Automatic Repair Mode. The screen informs you that Windows could not start properly and that you can use a System Restore point to attempt to repair the issue.

System Restore turns the clock back to a previous setup when Windows was working correctly. During the System Restore process, you don't lose any personal data that you added to the system. Instead, programs and apps that were installed after the latest System Restore point and time are uninstalled from your computer. The assumption is that a program or app may have damaged your operating system installation. By removing the programs and apps, Windows may be able to start properly.

If you decide to choose to restore, the process cannot be undone. You have the option of canceling, but you must do it from this initial screen; don't try to cancel after you start the restore process. If you decide to cancel, click the Cancel button now.

To continue, click the Restore button and respond to the onscreen prompts.

Repair Windows 10 Install

If you have Windows 10 on a DVD, you can boot from that disk and do a repair installation. Put the disk in the DVD drive and start the computer. Watch the screen for the message “Press Any Key to Boot from CD or DVD” (or a similar message); then press Enter or the spacebar.

If the option to boot from the CD or DVD never appears, and the computer doesn't boot from the disk, you need to change your BIOS options to boot from the CD/DVD drive. How you do that varies from one computer to the next. Typically, you start the computer and then immediately start pressing the F1, F2, F12, or Del key repeatedly as the computer is starting. (Try each one in turn, rebooting each time if necessary, until you identify the right key.) This should take you to the BIOS Setup options where you can configure the computer to try booting from the CD or DVD before trying to boot from the hard drive. Close and save the new settings. The computer restarts, and this time you should be able to boot from the Windows DVD.

If you can boot from the DVD, the first screen you see very likely asks about your language and locale. Make any necessary changes and click Next. On the next page, click Repair Your Computer (not the Install Now option). Then follow the onscreen instructions to do a repair install of Windows 10.

Advanced startup

If you can boot into Windows 10, but you're having issues with the boot process, consider using Windows 10's Advanced Startup tool. This tool assumes you can boot into Windows and navigate to the PC Settings area.

To use this tool, perform the following steps:

1.  Click or tap the Start menu and choose Settings.
2.  Click Update and Security.
3.  Click Recovery, and then click Restart Now in the Advanced Startup group, as shown in Figure 5.1.
4.  After Windows 10 restarts, it displays a screen similar to the one in Figure 5.2.
5.  Click Troubleshoot.
6.  Click one of these options (see Figure 5.3) and respond to the onscreen prompts:
   • System Restore: Use this option to restore your PC using a previously created restore point.
   • System Image Recovery: Recover Windows 10 using a recovery image file.
   • Startup Repair: Restart the device and perform a diagnostic repair.
   • Command Prompt: Open a command prompt to use console commands for troubleshooting and repair.
   • UEFI Firmware Settings: Configure firmware settings.
   • Go Back To the Previous Build: Use this option to revert to a previous build of Windows 10 (think of a build as a set of updates to the Windows 10 code, or as a Windows 10 mini-version identified by its build number). Microsoft releases new builds periodically, and using this option restores Windows to the previous build.
   • Startup Settings: Configure Windows startup behavior (see the following section).

Start in Safe Mode

For many experienced Windows users who have dealt with faulty Windows startups, Safe Mode has become a close friend. Safe Mode offers a way to start Windows in a barebones setup. This means Windows starts with just enough system files, programs, and services to allow it to run so you can diagnose issues, remove programs, and perform other tasks that can be done only at the graphical user interface level.

To enter Safe Mode in Windows 10, access the Advanced Startup options as described in the previous section. Click Troubleshoot, click Advanced Options, and click Startup Settings. On the resulting page, click Restart.

Although Safe Mode looks like a normal instance of Windows, many programs and features do not work. It is simply a place where you can modify system settings, such as those for Device Manager, MSCONFIG, the Windows Registry, Control Panel applets, and the like. You cannot, for example, start some Windows apps or other programs.

After you finish repairing Windows, shut down Safe Mode and restart normally.

Another way to boot into Safe Mode is to set Windows to do so at reboot. To do this, press Windows+X and choose Run. Type MSCONFIG in the Open dialog box and click OK. The System Configuration dialog box appears (see Figure 5.4).

Select the Boot tab and click the Safe Boot option. Click Apply and then OK. You're prompted with a dialog box that has Restart or Exit without Restart buttons. Click Restart so that Windows reboots. When it restarts, you're in Safe Mode. Use Safe Mode to diagnose or repair Windows.

When you want to leave Safe Mode, you need to undo the Safe Boot option in the System Configuration tool. To do that, press Windows+X, choose Run, and enter MSCONFIG. On the Boot tab of the System Configuration dialog box, clear the Safe Boot option and click Apply; then OK. Click Restart to shut down and restart Windows into its normal view.

The instruction manual that came with your computer

Most computer manufacturers provide some means of helping you troubleshoot and repair startup problems. Be sure to look through your computer's documentation and find the manufacturer's recommendations. That's your best bet because all computers are unique in some ways. The manual that came with your computer provides information that's specific to your exact make and model of computer.

Resources in this book

We've thrown lots of technical terms and concepts at you in this chapter. But when you're solving startup problems, learning some new terms is unavoidable. Here are some additional resources in this book that may help you solve a startup problem:

• Restoring from previous file versions: If you've backed up your entire hard disk using File History, see Chapter 19 for information on restoring from that backup.
• Restoring to an earlier time: For information on restoring your computer to an earlier time, see “Using System Protection” in Chapter 19.
• Removing programs: If you think a faulty program may be preventing your computer from starting, you can uninstall the program using techniques described in Chapter 25 (assuming that you can get to Safe Mode so that you have access to that program).
• Removing hardware: When faulty hardware or drivers are preventing Windows 10 from starting, techniques described under “Removing Hardware” in Chapter 29 might help.
• Troubleshooting hardware: Startup problems are often hardware problems. See Chapter 32 for more information on troubleshooting hardware.

Resources in Windows Help

If you can start the computer in Safe Mode, you can get to Windows Help. The Help window should open automatically as soon as you enter Safe Mode. If it doesn't, click the Start button and choose Help and Support. Then search using the keywords “Safe Mode” for additional information on using Safe Mode to troubleshoot startup options.

Online resources

If you can start in Safe Mode with Networking, you can access online resources. Try searching Windows Communities (which you can get to from Windows Help) for words related to the startup problem, or post a question describing the problem in as much detail as possible.

In addition, you can search Microsoft's website for words that describe the problem you're having. Be sure to include the number 10 in your search. Otherwise, the search result very likely will include other irrelevant Microsoft products. Starting your search from http://support.microsoft.com helps limit the search to Microsoft rather than including the entire web. If that doesn't help, try searching the entire web from www.bing.com, www.google.com, or your favorite search engine. If you aren't a technical person, don't expect the process to be easy. As we said, startup problems can be difficult to troubleshoot, even for the pros. If all else fails, you may have to take the system to a repair shop. Or call a mobile service that sends a computer geek to your home or office.