Since you don't have any BTC address posted by that account, it's very unlikely that you can recover that account.
I don't think that's really true anymore. An user on the Portuguese board recovered his account without any signed message. He had mentioned a few addresses but none of which he controlled. They recovered his account based on his IP addresses, email address, etc... and OP most likely has access to his original email.
I seen that he sold an (3D printer) asking for payment by cash pickup;
https://bitcointalk.org/index.php?topic=1344318.0