Things You'll Need
Instructions
Turn on an Xbox and a controller. Press the "Guide" button on the center of the controller then press "X" to sign out.
Press the "Guide" button again and select "Recover Gamertag." Confirm that you wish to continue.
Sign in to Windows Live using the Windows Live user ID and password associated with your profile.
Let the gamertag be recovered and select "OK" when the process has finished. You can now use the gamertag on the console.