If some Windows functions aren't working or Windows crashes, use the System File Checker to scan Windows and restore your files. Though the steps below might look complicated at first glance, just follow them in order, step-by-step, and we’ll try to get you back on track. Run the System File Checker tool (SFC.exe) To do this, follow these steps:

If Windows 8 is successfully activated, software version information and the expiration date will be displayed. If you have activation problems, you can find out whether your Windows 8 system is successfully activated or not through the above checking.

Windows 7 and 8.1: Run a troubleshooter. Update the device driver. Error codes in Device Manager. If the above steps didn't help you resolve your problem or were not available, locate your error code in the following table, and follow the recommended resolutions for that error code.

To fix problems using Windows Update: Select Start > Settings > System > Recovery > Fix problems using Windows Update. After you select the Reinstall now option, choose if you want to allow the PC to automatically restart 15 minutes after the installation completes.

Learn how to update your device at update Windows. Use the Activation troubleshooter to resolve simple errors. For more info, see Try the Activation troubleshooter below. If you're still getting an error, check the list of error codes below and follow the suggested steps to resolve it.

You can find the error code for the failed update by viewing your update history. Look for KB 2919355 in the list, note the error code, and then contact Microsoft support . To view your update history:

If you get an error code while downloading and installing Windows updates, the Update Troubleshooter can help resolve the problem. Select Start > Settings > Update & Security > Troubleshoot > Additional troubleshooters. Next, under Get up and running, select Windows Update > Run the troubleshooter.

You can find the error code for the failed update by viewing your update history. Look for the update that wasn't installed, note the error code, and then contact Microsoft support . To view your update history in Windows 8.1:

If you are receiving an error message with a specific error code, try running the Windows Update Troubleshooter. If that doesn't resolve the issue, see Fix Windows Update errors and follow the instructions to help resolve common update issues.

Blue Screen errors (also sometimes called black screen errors or STOP code errors) can occur if a serious problem causes Windows to shut down or restart unexpectedly. You might see a message that says, "Windows has been shut down to prevent damage to your computer" or a similar message.