ID blocked
Why is my Apple ID blocked from App Store and iTunes
Question marked as
You know that we are fellow users, why would you think anyone on here would know why ?
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 in the country where you are (and which is therefore the country on the account) and see if they can/will re-enable it : http://www.apple.com/support/itunes/ww