Sometimes designers get bogged down with sheer volume of work. How long have you been out of contact with him?
But....
The site whois = "Domains by Proxy, Inc" so there's no telling what country he's in.
You could also put the ICQ number through Google
http://www.google.com/search?hl=en&q...=Google+Search
to see what other boards he posts on.
Last resort may be to contact the host of his site requesting contact details.