Normally, when you boot your PC, the operating system is loaded from a storage drive physically located inside your PC. Whenever I want to try a new operating system, all I need do is copy the operating system ISO file onto the drive. Related 4 repair commands to run before you reinstall Windows Reinstalling Windows is disruptive. From there, the usual installation process can take over, and you'll have a fresh operating system in a few minutes. I frequently tweak my Windows PC to the point of badly breaking things, and on more than one occasion, I've had to perform a complete reinstall.