Why can I not update my payment details?

A few days ago I went to update an app that I have in my phone and when I went to update the app my phone then asked for me to update my payment infomation when it has been the same since I have had the phone(2-3 years). When I go to update and put my payment Infomation into my phone again it then advised me that the details have been declined. I now cannot update or download any apps at all, I also have games which I have spent years playing with friends from around the world which I now have no access too can someone help please.

Many thanks.