It helps to post exact error messages when asking a question here. It helps us track down exactly the right support article.
Maybe this one? --> If your payment method is declined, or you have a billing issue with a previous purchase in the iTunes Store - https://support.apple.com/HT203005 - additional information: https://discussions.apple.com/message/31245423#message31245423
Create or use your Apple ID without a payment method - https://support.apple.com/HT204034
Clearly you will need to resolve the problem with money owning on a purchase before you can do anything. You can pay with either a credit card, sometimes other options, or redeeming money to your account with a gift card.
If you still need assistance:
iTunes [Store] Support - Use this form for assistance with account and billing, code redemption, or purchase questions --> https://www.apple.com/emea/support/itunes/contact.html