iMessage on Macbook Deactivated

I recently took my computer in because it appeared to have crash, as it did. So they reinstalled a new hard drive. By our coinicidence my computer crashed not eh same day that I upgraded to an iPhone 6 plus from a 5S. I also switched cel phone carriers. Now when I try and log into iMessage on my computer to set it up, it says that my account has been deactivated and i need to change my password at Iforgot.apple.com. Which doesn't help. I have verified the email on my iPhone. HELP!!!