Instructions
Recover Your Gamertag
Turn on your Xbox 360 and don't sign into any Gamertags or profiles.
Open the "Home" menu by pressing the "Guide" button.
Use the left thumbstick to highlight "Recover Gamertag," then press "A."
Highlight "Recover Gamertag" again on the resulting pop-up introduction window, then press "A."
Select "Yes" when asked to sign into Xbox LIVE and launch the recovery wizard.
Enter your Gamertag into the "Gamertag" field then highlight and select "Continue" to advance to the next prompt.
Enter your Windows LIVE username and password into their respective fields then highlight and choose "Sign-in."
Review the resulting terms of use document then highlight and select "Accept." Your console will then begin the Gamertag recovery process, which can last several minutes as the console downloads your Gamertag information.
Renew Your Subscription
Log into your Gamertag and connect to Xbox LIVE.
Select "My Xbox" from the dashboard by highlighting it and pressing "A."
Go to "Manage Account" and press "A."
Highlight and choose "Memberships," then select your Silver membership from the resulting "Memberships" screen.
Highlight and select "Modify Membership," then choose to upgrade to a Gold subscription.
Input your prepaid card's code or your credit card information to finish upgrading your account to Gold again.