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.
Windows XP:
Start - all program - accescories - system tool -system restore
In windows xp you will have 2 option to restore or to create. Select restore to restore your computer into previous state and you will see there dates you can select with description of what changes have been made on that time. Select the preferable date dan continue until it reboot and finish restoring your computer. You can also undo the restore if you not satisfy with the result.
Windows Vista and Windows 7
Start and on the search box type system restore. Select system restore form the result.
Similar with windows XP, there are several dates you can choose from, and the will be description what changes on what time. Select the date and click next to continue with system restore.
Windows 8:
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.