There are two ways to have your Windows 7 computer restored to earlier date:
- System Restore from backup you made before
- System Restore to last restore point made by Windows - restore points that are made automatically by installing new software, windows updates etc...
In case you have done backup when your system was healthy and now you would like to use that as restore point you should open Control Panel ( Start-C.Panel ) than from "System and Security" choose "Backup and Restore". New window should appear with option to restore from backup available or locate backup you made before.
Another way is to use your last restore point available made by Windows. This is second option we mentioned above and it will undo recent system changes but leave files such as document, movies and music unchanged. Again use this with caution and be aware this might remove recently installed programs and drivers.
Go to Start-Control Panel - System and Security and click Restore your computer to an earlier time that is located under Action Center as shown on picture below. Open System Restore and choose date to restore.