How To backup registry files
First of all you need to backup all your registry file before modifying them because if you made a wrong editing it will help you restore original files. Secondly you must have basic knowledge about editing and modifying registry. You can backup the whole Registry and only Registry sub-keys.
Procedure for editing registry
Click Start Button then click run, type regedit in Run dialog box and click OK button. Here you can backup the whole Registry or you can locate the required sub-keys that contain the information that you want to edit.
Go to File menu option then click on Export option for backup and save it with on any your system drive with . Reg extension and you can restore this backup going File menu using import option.