That account mexmer was active just 3 days ago. What happened since then? Are you sure he didn't get banned or something?
And yeah, I'll echo the above and tell you that unless he can sign a message from that one address used to apply for the campaign, he can forget about recovering the account. Even if he does do that, I don't even know what the chances are he'll get it back in his lifetime. The recovery process is abysmally slow here.
looks like we don't have access from that address from 2 years ago. but it dosen't make sense we have access to email and password of this account it should be the best way to confirm ownership than an address from 2 years ago