Question marked as
Best reply
The message means what it says, the account has been disabled for use with the stores - but nobody on here will know why a particular account has been disabled (but the most common reason is likely to be too many incorrect password attempts).
Try resetting its 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 : https://www.apple.com/emea/support/itunes/contact.html