This happened to DesurtDawg a few years back. His old computer died and when he got a new one he could not for the life of him remember his account password. Until he stumbled across it last year, there was nothing site support could do for him. I think you need to access your account again before they can help you.
I'm sorry if that doesn't seem helpful. From the site's perspective, though, they can't just merge an existing account without a specific request from that account. Otherwise, anyone could make a new account, claim to be an author who has gotten locked out of the system, and then steal all their work.
Is there any chance you could find that old password somewhere?