I hope i can help you.To enable it back, you have to reset the password of your Apple ID. Reset it from here: http://support.apple.com/kb/HE36Also, refer this article: http://support.apple.com/kb/TS2446Let me know if you have any questions.
I already did that. The account was hacked and the id and password were changed by unauthorized user 2 days ago. I contacted apple and changed the password and they reinstated the ID, however when i go to use my ipad/iphone i get the message "your apple id has been disabled"
Have you tried resetting your Apple password from your iPhone itself ?