We often give a tip or trick that requires you to edit the Registry. It's always a good idea to back up the registry before making any change. The fastest way to do this is to back up the Registry key to which you're going to make changes. Here's how:

1. Click Start, then click the Run command. Type Regedit in the Open text box and click OK.
2. As an example, go to the following Registry key:
   HKEY CURRENT USER\Software\Microsoft\Windows\CurrentVersion\UnreadMail
3. Click the File menu and click the Export command.
4. In the Export Registry File dialog box, type in a name for the backed up Registry key in the File Name text box. Click Save.
5. If you ever need to restore the Registry to the state it was in before you made the change, just double click on the file you saved. This will undo any modifications or deletions you made to the key. It will not remove additions (such as creating a new value).

This method is used for exporting a single key. Don't try to export the entire Registry or an entire "hive" (the highest level folders in the Registry hierarchy). If you want to back up the entire Registry, use the Windows Backup utility (Start | Programs | Accessories | System Tools) to back up the System State.

Check out this article on how to back up, edit and RESTORE REGISTRY settings.