My App Store won't let me download anything

ok, so ive had my phone for js over a year and like four months into having the phone the app store js like stopped letting me download/update things, every time i try to do either of those things it pops up with a tab that says "verification needed" then after i give it my password it comes up with a tab that says "billing issue" or smth like that and ive tried taking out my billing info ive tried putting it back in, ive canceled all of my old subscriptions and it still wont let me download anything. and its really stressing me out. what do i do?

[Re-Titled by Moderator]