Can I put my money from iTunes back onto my card
I would like to know if it’s possible to put the iTunes money I have in my App Store back onto my card
You will have to ask Apple if they are prepared to do this for you. Normally once funds are in Apple Account balance the only way to get them out again is to spend them.
Click here --> https://support.apple.com/choose-country-region/media-services Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.
or:
Contact Apple for support and service --> "See a list of Apple phone numbers around the world."
Click here --> https://support.apple.com/HT201232