Try resetting the account's password (and then logging out and back in everywhere) : If your Apple ID has been locked - Apple Support
If that doesn't fix it contact iTunes Support and see if they can/will re-enable it : http://www.apple.com/support/itunes/ww or https://www.apple.com/emea/support/itunes/contact.html
Just call the Apple support and they will unlock it for you as they just unlocked it for me few minutes ago
When I try to buy something in the Apple Store, I get a little notification saying “Your Apple ID Has Been Disabled.” I don’t know how to fix this. I tried going into my settings but it says that my Apole ID is enabled for purchases.
