Account disabled in App Store & iTunes

I have recently faced an issue with my account in the App Store and iTunes. Every time I attempt to download an App or make an in-App purchase the following message pops up “Your Account has been disabled in the App Store & iTunes”.

I have tried following some steps suggested by people who have faced similar issues, such as, resetting my Apple ID password through Safari, but still no luck!

I can sign in and out of my account with total ease, so I have not been locked out. I simply cannot download anything, make purchases or update any apps, which is very frustrating.

How do I resolve this issue?

Thanks in advance - :)