This sounds complicated, but a simple answer is do a clean install.
Clean Install Windows 7
The complication is, you had someone elses Dad do 'something" and now it has different problems. I'd talk to him, but the question arises, do you have the installation DVD for the Windows 7 that came on your PC? Or did this Dad use something he had? the easiet thing would be a clean install, but if the Dad did that, he'd know what he used, etc. A Guy