The System File Checker can help fix many types of corruptions and problems with your copy of Windows.
Sometimes you’ll find that you have corrupt, damaged, or missing files in Windows that are causing bugs, problems, or perhaps even blue screens. Faced with the possibility of reinstalling the operating system and all your software what can you do? Well there’s a hidden tool that might just repair the problem for you.
From the Start Menu, run Command Prompt (Admin) and then type the command SFC /SCANNOW. This will run the System File Checker, which will check every file that makes up Windows to see if any are corrupt, missing, or have been tampered with. If it finds any that need replacing, it can copy the correct version of the file from an installation DVD (note it doesn’t currently work with Windows Update or USB installation media).
You will need an up to date copy of the Windows installation DVD, to ensure the files copied are the latest versions that match those on your PC, but Microsoft have made it easy to get the latest DVD images (called ISO files) and you can download them for Windows 10, Windows 7 (for which you’ll need your Product Key) and Windows 8.1. On a PC with a DVD burner (internal or attached by USB), right-click on the downloaded ISO file and select Burn Disc Image from the menu that appears, to create your disc.