I've been there, I didn't think the kits were big enough to get out of their drawer and I left it open, came home to find zero kits in the nest, Louie and Della snuggling on the floor next to the drawer, "we've made a mistake, please put us back", Lady G I finally found cuddled in a corner (they were what, 13 days old? 15?) by herself, very chilled, and then for the life of me I couldn't find Pipsqueak! So I started in the room and picked up every piece of furniture, moved the dresser and used a flashlight to make sure he wasn't hiding under the dresser (you can get under from the back and being so small.. he could have.) finally after going around the floorboards and finding nothing I moved on to the doors. Which doors had the largest cracks underneath? Bathroom first. Easy search, nothing. Closet next. Oh boy. Closet is the catch all so I just started at the sides and worked my way inwards. I found him wedged up between a crate and the wall, very cold but alive.
Does Snickers squeak yet? Because Pips heard me talking and squeaked at me. So talk, croon as you're looking. They can slip under doorways so just go methodically. Search EVERYTHING.
Good luck.