As far as I understand the ownership of my email account is not a proof of my account ownership on this forum and I never posted any of my bitcoin addresses on this forum.
The hacker changed my email address, so I can't change my password or login.
What was the point of sending me an email to lock my account? I locked it but I can't unlock it? What is going to happen to this account?
The procedure for recovering lost accounts requires you to have a valid signed message from an address that you have previously posted on this forum. I'm pretty sure that unless otherwise stated, this is your only chance of recovering your account, since it is the only definitive proof that you have previously owned the account.
Did you ever send a PM to another person with the address in it? If yes, then ask that person to dig out that old PM. That *could* be a valid proof that the address was owned by you as well.
I have no idea what the "locking" email is about, but did you already lock your account? What's your username? If it's locked then the features on forum I'm assuming shouldn't be available to the hacker.
