Why don't you try and get a special treat, like chicken or steak. See if he will take it. Perhaps you cab bring on of your pups uout and see if they play? Can you take him/her in untill a good home can be found?

Do you have a dog house or something he could sleep on outside your door if you say he won't come? It seems like he may be scared.

Contact the local shelters and see if anyone has reported him missing. Also contact animal hospitals and rescue organizations for the same reason.