My iTunes card balance is no longer on my Apple ID account
I added an iTunes card, but my balance disappear. I threw out the card and now I don't know how to get the $$ back. It was a birthday gift
iPhone 5s, iOS 7.1
You've tried logging out of your account on your phone by tapping on your id in Settings > iTunes & App Store and then logged back in to see if your balance then shows ? And you didn't owe iTunes any money and/or have any pre-orders or auto-renewing subscriptions that might have used the balance ? You can view your account's purchase history via your computer's iTunes : log into your account on your computer's iTunes via the Store > View Account menu option, you should then see a Purchase History section with a 'see all' link to the right of it. Click on that and you should then see a list of your purchases.
If you can't find where the balance went then try contacting iTunes Support and see if they can help : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then Purchases, Billing & Redemption