Well, this forum has been hacked before though I'm not suggesting it was in this case. You might have picked up a keylogger or something like that, who knows. I don't. Be careful and don't trust anything around here.
It's been quite a while since that hack. If you did not change password since then it would possible I guess but they seemed to go after special accounts when it happened, like Mt. Gox and some other big name accounts.
I guess no matter reason you will need to find something where you posted a bitcoin address and can prove you still own it through signature. Best is if you staked an address if not it will be harder to find one. Others reading if you have not staked and address you really should. Also it can be a slow process to get account back.