Back up the registry
You must be logged on as an administrator to perform these steps. If you are not logged in as an administrator, you can only change settings that apply to your user account.
Before you make changes to a registry key or subkey, we recommend that you export, or make a backup copy of, the key or subkey. You can save the backup copy to a location you specify, such as a folder on your hard disk or a removable storage device. If you make changes that you want to undo, you can import the backup copy.
Open the Registry Editor by clicking the Start button , typing regedit into the Search box, and then pressing ENTER.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Locate and click the key or subkey that you want to back up.
Click the File menu, and then click Export.
In the Save in box, select the location where you want to save the backup copy, and then type a name for the backup file in the File name box.
For advanced information about editing the registry, go to the Microsoft website for IT professionals.
Although you can back up more than the registry key or subkey that you are modifying, doing so adds to the size of the backup file.
Before editing the registry, it's a good idea to create a restore point using System Restore. The restore point contains information about the registry, and you can use the restore point to undo changes to your system. For more information, search Help and Support for "System Restore."