I have a new card with a new number. How do I change my card number?

Follow the steps here: link-> Change, add, or remove Apple ID payment methods - Apple Support

I have a new Master Card number for paying my account. How do I access my account?

MrGeorges wrote:

I have a new Master Card number for paying my account. How do I access my account?

Follow the steps in the link provided in the very thread you replied to.