Ok. Strangely enough, this being my first post here, I am not going to talk about airplanes, lol.
Your best bet for a "reset" of Windows, is to use the Windows System File Checker tool. To use it, open your run function (In Windows 7 it is click on the Windows Start Button, select run), type in the following: "SFC /scannow" (without the quote marks) then hit enter.
Here is the official Microsoft Page about this.
https://support.microsoft.com/en-us/kb/929833
That command will repair and/or replace all corrupt Windows files without having to reinstall.
I have no idea which version of Windows you have, but just research the above and you should find out if, and how well it will work for your flavor of Windows.
Hope it helps.