Im sorry to hear this has happened to you. Check all around the emmidiate areas of your tank. My Snakey got out back when he was younger and was on a nearby bookshelf, lol. And if you stil cannot find him put a cage with live mouse on the ground and your snake should be interested in them. When I bred rats I kept them in these small cages (not tanks) and the snakes could really smell them. So I got a couple live feeder mice and stuck them in a spare cage and put them on the floor of the snake room(remember to shut your door) So your snake should also be attracted to the cage of food. This works, but make sure the bar spacing is just right so your snake doesnt get bitten by the mice, or tries to go inside them (DO NOT USE RATS). And so you snake does not try and forces his way into the cage put some cloths and towels around the cage(so the snake can hide in) and put one of his hides on the ground. Good luck!