Unless you aren't there to hear it!
I've found all of my escapees within hours. Keep looking. Search EVERYTHING. start close to the enclosure and work your way out. Check boxes, subwoofers, cabinets, shoes, behind books, clothes, etc. etc. Don't leave a single thing unturned, the snake will be there.
Everytime I think I've looked everywhere, there is one or two spots I miss and the snake is always there. I've only had 2 escapes... all due to human error. D'oh!