Can admins help me recover deleted messages?
Why didn't I get messages to my email like I did before?
How can I unblock OP?
Cannot help you with the first two questions, but as for unblocking the OP, go to your Profile, on the bottom left, click "Personal Message Options", you will find a list that will contain any users you (or the hacker) have added to the ignore list. Remove the name from the list, click "Change Profile" on the bottom right, and you will now be able to communicate with each other again.
On another note, as another user pointed out - You need to do a full scan on your system using a good anti virus such as Bitdefender or Kaspersky. You may have some malware on your computer.