Turn back the clock with System Restore (Windows)

The System Restore feature enables users and administrators to restore a computer to a previous state without experiencing the loss of any data. This feature enables you to undo any changes you've made to your system's hardware, software, or settings that have left your computer in an undesirable state.

All you need to do is first launch the System Restore program. Simply click the Start button and choose All Programs | Accessories | System Tools | System Restore. The System Restore feature monitors and tracks changes you've made to your system and, at specific intervals, automatically creates restore points or checkpoints when events such as program installations occur. These checkpoints, automatically created every 10 hours your computer runs regardless of whether you've made any major changes to your OS, tell Windows to return your system's settings to this point in time should the operating system experience any problems. You can apply these automatic checkpoints to your system by selecting the Restore My Computer To An Earlier time option button. Then, select the restore point of your choice, click Next, and then click Next again to restore your system to its last healthy state.