he's just gone from the company, not dead. We had almost the same thing happen, guy left and noone knew what to do.

There's always the thought that someone leaves you can't talk to him any more, like he has leprosy or something, and that's not true.

The fastest way is to simply call him on the phone; chances are he'll know it off the top of his head.

After you get the information, you'll want to start documenting things so it's easier to recover from in the future.