Fixing corrupted SAM File in Windows 7

In a Windows 7 PC, I encountered a problem where someone had tried to edit C:\Windows\System32\config\SAM file and the PC was not starting but giving a blue screen.After a long research, I found the simplest solution here. In config folder, there exists RegBack folder and backed up SAM Files residing in it. So all you have to do is to copy those SAM files back to config folder and you can login the system with previous login credentials.