1.Step by step click Start>Computer>Properties.
2.On the left pane Click on System protection.
3.Go to System Protection and click System Restore, then OK.
System Restore is a feature in Windows 7, Windows Vista, and Windows XP that allows you to revert Windows to a recent point when everything was working fine. It lets you undo changes to the Windows system without altering personal files.
1.Click Start and type "restore" into the Search box. Select "System Restore" from the top of the search results list.
2.Choose your restore point. Windows will automatically select the most recent restore point in which something was installed or changed. The change will be displayed underneath the date the point was created.
3.Confirm that you want to restore. When you select your point, you will be given one more chance to ensure that you want to proceed. Review the point you selected and click the "Finish" button and then "Yes" to start the restore.
4.Wait for the restore to complete. Your system will reboot and the restore process will begin. Be patient, as the restore process can take a while to complete. Once the restore is finished, Windows will load and you will be shown a message confirming that the restore was successful.