try this thread http://www.reptileforums.co.uk/snake...-know-how.html
is this a corn snake we are talking about? even hatchlings can go months without food, so dont give up, i lost a young corn for 8 months when i was a kid, and it turned up just hanging in the curtains, its crazy how long the stay active and well for. there is some good tips on that thread above. good one is putting lines of flour down on the floor at night, then in morning u will be able to see if the snake is around cos the flour will be smudged and it helps u determine what room the snake might be in etc.
good luck xx