I've lost snakes before, only found one of them. Though the smaller they are the easier it is for them to get outside. How big is he/she?? Try staying up late with all the lights off, but one heat lamp and hang it off a chair near the floor so as to make a basking spot. You can use a smaller light to read by if you need, but no others!! Turn all the heat off and he/she will probably come. This is the only way I have ever found a snake that has been gone awhile.