How to Back Up the Windows Registry
Before you edit the registry, export the keys in the registry that you plan to edit, or back up the whole registry. If a problem occurs, you can then follow the steps how-to restore the registry to its previous state.
How to Export Registry Keys
Click Start, and then click Run.
In the Open box, type regedit, and then click OK.
On the File menu, click Export.
In the Save in box, select the boxs at the bottom the bottom according to weather you want to export all or only selected branches of the registry.
Next select a location in which to save the backup .reg file. In the File name box, type a file name, and then click Save.
How to Restore the Registry
To restore registry keys that you exported, double-click the .reg file that you saved.