No matter why you're restoring a previously backed up registry, congrats on being proactive and doing just that before you made your change.
Follow the easy steps below to restore backed up Windows Vista registry data:
Note: The following steps require working in some way with the Windows Registry. Making changes other than the ones described below could cause system problems.
Locate the Registration File you exported before making your changes to the Windows Registry.
Having trouble locating the file? Assuming you actually did make an export from the registry, look for a file ending in the REG file extension. Check on your Desktop, in your Documents folder, or in your C:\ drive.
Double-click on the REG file to open it.
You'll next be prompted with a message in a Registry Editor window:
Adding information can unintentionally change or delete values and cause components to stop working correctly. If you do not trust the source of this information in [REG file location], do not add it to the registry. Are you sure you want to continue?
Click the Yes button.
Important: This isn't a message to take lightly. If you're importing a REG file that you did not export or one you downloaded from an unknown source, be aware that you could cause damage to Windows Vista.
Assuming the restoration of the registry keys was successful, you should receive the following message in a Registry Editor window:
The keys and values contained in [REG file location] have been successfully added to the registry.
Click the OK button in this window.
The registry keys contained in the REG file have now been added to the Windows Vista Registry. If you know where the registry keys were located, you can open Registry Editor and verify that the changes were made successfully.
Restart your computer. Depending on the changes that were made by restoring the registry keys, you may need to restart to see the changes take effect in Windows Vista or in your programs.