When you/he or whoever bought the computer you should have(if you payed extra for these) received recovery discs. I don't know if it is the same for every computer(the amount of recovery discs) but I received two. If the people who did it were smart enough to label them "1" and "2" then you can do this easily. First you put the "1" disc in your computer, then when that disc is done(it will seem like it is downloading something...kind of) you put in the "2" disc and then when that one is done, wa la! BAM! You're fixed(you have to choose a date to reset the computer back to during this operation). If you have a hard time doing this just call the manufacturer of the computer or Best Buy/Geek Squad.
EDIT: What this is doing is pretty much reseting the computer to the way it was when you bought it, all files and everything you had on it will be lost I am pretty sure of that!
**If your computer is old enough it may not have come with these 'recovery discs'.**
If this helped then +rep me

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