Oh dear, i know exactly how you feel as we managed to loose a 4ft royal once. She had got under our floor boards as we had a whole at the time we was fixing!
Will give you as much help as i can. First of all read this
Its how to make a snake trap, brill for small snakes!
Heres a few more tips to help
- Check dark warm places, under beds, sofas, radiators, vivs, under fridge. Re-check often.
- Leave out water bowls as they will search for water, they often turn up in bathrooms as warmer and has water
- Leave out lots of hides, and check them daily
- Leave out a heat source eg heatmat as it may attract them to warm up.
- Leave out food eg pinkie mice as smell may attract them too if hungry
Hope this helps x