My neighbour had the same problem with his newest expensive laptop. He probably installed some registry changer and that's how it was fucked up. I suggest you to try repair discs and browse google around. Or if you got still warranty, go to the company, wait like a week and they will repair it for you for free (Atleast here it's free.)
I got a 9mm, ready to go off any minute, because of the ban I had to delete it but if you fuck around you gonna make me respawn it eh