You can use a Vista recovery disk to restore your computer to its original factory settings. This is a disk or set of disks that are designed to completely erase your hard drive and reset your computer to the day you bought it. The recovery disk commonly comes with your Windows system when you buy it. If you do not have one, you can easily create your own recovery disk. Outlined below are the steps you need to follow in order to reset your computer.
Note: There are slightly different instructions from different manufactures, but these steps provide a general overview of the whole process.