To restore your system from a restore point, follow these steps:
Click the Windows Start button and select All Programs > Accessories > System Tools > System Restore.
When the System Restore window opens, check the Restore My Computer to an Earlier Time option, and then click Next.
When the Select a Restore Point screen appears, you'll see a calendar showing the current month. (You can move backward and forward through the months by clicking the left and right arrows.) Any date highlighted in bold contains a restore point. Select a restore point, and then click the Next button.
When the confirmation screen appears, click Next.
When the process is complete, your system should be back in working condition. Note, however, that restoring your system is a time-consuming process. It might take a half-hour or more to complete a system restore.