In order to restore your system restore tab, you will need to edit the registry. Be sure that you make a backup copy of the registry prior to making any changes.
Go to Start>> Run. Type in: regedit [Enter]
Navigate to the following registry key;
HKLM\Software\Policies\Microsoft\Windows NT\SystemRestore
Single click once on the entry; "SystemRestore" to empty its contents into the right pane.
Find the entry "DisableSR", right click on it and delete it.