Hi,
Please follow this instructions.
Step 1: Click on Start, All Programs, Accessories, System Tools, and click on System Restore.
Step 2: Click on the Create a restore point radio button and then click Next.
Step 3: Give a new name to the restore point.
Step 4: Now click the Create button and your restore point will be created.
Now if you ever need to revert your computer back to a previous state, just run the System Restore tool again and choose “Restore my computer to an earlier time”.