Why and how is my App Store account been disabled?

If you see a message that says "Your account has been disabled in the App Store and iTunes", there is a problem with your payment method on your account, to resolve the problem you need help from Apple support,  click -> contact Apple Support for help.

Additional:

Try to optimize the range of the mobile network, see this Apple article:

If you see No Service, Searching, or SOS on your iPhone or iPad

If you see No Service, Searching, or SOS on your iPhone or iPad - Apple Support