Without an address to sign a message you're pretty much SOL on account recovery, sorry dude 
if he did some trades via pms and have address in that pms that can be considered ? Yes definitely.
https://bitcointalk.org/index.php?topic=642008.msg7169449#msg7169449
It's best to include it naturally in a post. But if you can't, you can send a PM to an account that won't delete it (you could use DefaultTrust for this). After you send it, check your outbox and make a note of the PM's ID (visible in the quote URL).