Why does it say your account has been disabled in the App Store

The answer to “why” is because there is a problem with your account or the payment method in it, so Apple disabled your account to get your attention to fix it. But what you really want to know is not “why” but “how to I fix it”, and the answer to that is in the Related Article at the top of this page that you were reading when you posted here in Apple Support Communities. Note that you MUST contact a live person at iTunes & App Store support to resolve the problem, as explained in the Related Article; you cannot resolve it on your own.

This is a user to user forum. We do not have access to your records so cannot answer your question. Please do as the link above your post suggests and contact Apple directly.

It reads: If you see a message that says "Your account has been disabled in the App Store and iTunes," contact Apple Support for help.