If you are stuck in a loop where the windows 7 does not boot and the system repair cannot fix your installation , it might be a good idea to run the system file checker.
However sfc doesn’t really understand what to do if you just run sfc /scannow from the advanced repair options command prompt. – We need to tell it where windows is installed.
So choose advanced repair options, command prompt and type:
SFC / SCANNOW /OFFBOOTDIR=c:\ /OFFWINDIR=C:\Windows
If you have windows installed on another drive than C, change it. For me it was E for example.
If you don’t remember where it is, type c: and hit enter in the command prompt, then type dir and see if you see a folder (A text line) that says Windows if not try again by changing the drive letter, to d: ,hit enter, type dir, hit enter and keep hunting for those files.