Rhonda, if you have Windows, it saves a copy of your hard drive each day or however often. Each "snapshot" it takes is called a restore point.
You can go back to a previous restore point using System Restore. If you have Windows XP, go into your Start menu --> All Programs --> Accessories --> System Tools --> System Restore and follow the instructions.
There is another way to do it using your Windows XP disk, if you have one, but I don't, so I don't know how to do it that way.