Windows 7 has a feature called System Restore which automatically backs up registry and system files whenever you install new software or drivers. In case of any problems, you can recover the system by using system restore.
How to restore Windows 7 using System Restore
Open the Windows Start menu and type restore. Open the “System Restore” program from the list
Click on the “Next” button. Click “Show more restore points”
This will give you a full list of all the restore points available, indicating the change whiich triggered the restore point
Select the restore point you need to roll back to then click on the “Next” button. Then press Finish then Yes to complete the restore. Windows will automatically restart during the restore process.
Note: What you’re sitting through here is the actual System Restore process. Do not turn off or restart your computer during this time.