Website or forum? Either way does someone halve offline contact info for anyone. If a forum, like my proboards one, you could contact them to see what happened. If website, try to buy the domain and i think you can find who hosted maybe. Dunno much on that one but if anyone can contact the owner you stand a chance of gaining control.
if you are able to get it, do like i have on my forum, three othere people have keys to the shed in case i die. I'm the only one that could delete but they can do everything else and i posted a 'will' in the moderator forum so hope probards would allow chain of succession to happen easily.