|Most computers have a way to return it to the way it was when you bought it. The owners manual will tell you if you need to create some dvd's or if you need to use a F key at boot or even if you need to order them from the factory. In any case that is the best way to start all over.|
All of that is kind of not what you problem suggests. Might try a "restore point" in Vista. See help and support for that from the Vista start menu.
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.