How to restore Windows to an earlier state using System Restore in Windows XP
Start System Restore. It is located in the System Tools section in the Start menu: Start -> (All) Programs -> Accessories -> System Tools -> System Restore.
Make sure the option Restore my computer to an earlier time is selected, then click Next.
Use the calendar to select the date (in bold) that you wish to restore to. Note that only the dates in bold actually contain restore points.
Once you select the desired date, on the right select specific restore point you wish to use.
On the next screen you will be presented with information about the process. We recommend that you read the information carefully, especially if this is the first time you are using the System Restore feature.
When you are ready, click Next.
Your computer will reboot, during which process changes will be applied.
After Windows starts up again you will see a window with a short summary before your Desktop is loaded. Simply click OK, and you will be returned to your Desktop.