I have read on here that placing a thawed mouse in a hide or over turned shoe box has worked for some people on here, I would also say be methodical ( something that can be hard to do if you are freaking out like I know I would be) and slowly check everything .. if there is a way to get into the heat vent I would check there, check your box spring in your room etc.

I have read a lot of post where people have found their snakes upstairs when they are kept downstairs. I hope you find the baby!