I had to change my id & have lost my gift card balance please help?

Did you change the Apple ID for an existing account? Or did you create a new Apple ID? If you created a new Apple ID, your balance will still be tied to the old account and you'll have to log into the iTunes Store using that old account to spend the balance. If you changed the ID on an existing account and can no longer see a credit balance, go here:

http://www.apple.com/support/itunes/contact/

and follow the instructions to report the issue to the iTunes Store.

Regards.