Use System Restore

System Restore is one of those programs that can be a life-saver when you've been the unfortunate recipient of unstable software, a badly timed power outage, or a damaging thunderstorm. System Restore records important documents, settings, and preferences on your computer. If the unthinkable happens and your computer files are damaged or inaccessible, you can use System Restore to restore your computer to the same state it was in before the data was lost.
System Restore creates restore points daily and whenever you install device drivers, automatic updates, and some applications. But it's a good idea to get into the habit of creating a system checkpoint (called a restore point) when you're about to install new software or take any action you suspect might make your computer unstable. Then, if there's any conflict at all, you can restore your computer to the point just before you began the installati

Create a restore point in Windows 7

1.      In Control Panel, click System.

2.      In the left pane, click System protection.

3. Click the System Protection tab, and then click Create

4.  In the System Protection dialog box     type a description, and then click Create