Windows repair is a all in one tweaking tool used to repair all knows bugs and registry error of windows operating system. It also removes malware infection in your PC as malware and other third-party software’s have many permissions to change operating system files. There are lot of other repair tool in windows like antivirus, firewall, windows defender which fix some of old issues because your windows might not get latest update or any other issues.
It can be done properly by booting into safe mode of windows because in safe mode most drivers, auto-run software etc are disabled so its ideal for fixing and deleting issue files. Windows repair tool works fine on safe mode for registry and driver errors.