Gift cards that were won through any contests are not usually refundable. However, you can try to do the following things:
1. check the contest rules if you can convert the gift card to cash
2. check with the organizers if they still have the receipts for the gift cards so that you may be able to refund it with the store where they purchased it
3. just sell the gift cards to your family or friends who might be interested to use it
I hope these helps you with your concern.
Happy New Year!