System Restore can return your PC's system files and programs to a time when everything was working fine, potentially preventing hours of troubleshooting headaches. It won't affect your documents, pictures, or other data.
What System Restore Can Do?
1. Undo any installed updates
2. Undo any upgrade
3. Undo changes you make and does not infecting your files and documents.
What Files Are Changed During System Restore?
System Restore affects Windows system files, programs, and registry settings. It can also make changes to scripts, batch files, and other types of executable files created under any user account on your computer.
Start - all program - accescories - system tool -system restore
Windows Vista and Windows 7
Start and on the search box type system restore. Select system restore form the result.
On start screen select restore point and on the search result select setting the select create restore point and you will be brought to the System Protection tab of the System Properties control panel.