escaped from his indoor cage can't be found

Hello

My bunny is a 6 month old male, not yet neutered. He lives in a large cage in my basement bedroom. He's out in my room frequently. I was gone overnight and when my mother fed him the cage door didn't close properly and he's nowhere to be found. I can't hear him or see him anywhere. It's been over 12 hours. Will he return to his cage on his own? What might he be doing? Could he be dead? I'm getting worried and don't know what to do.