To locate your Cardholder ID, look at the back of your Discover Gift Card. You'll see a number printed in the area where you sign your name. Enter the last 3 digits of that number in the field.
In order to replace your Discover Gift Card if the card plastic has expired or if you lost your gift card, call Customer Service at 1-866-522-7026.
The fees vary depending on what type of Discover Gift Card you have.