put some hamster food around your house. then next day check see
which area's food got eaten. then you'll roughly know which room
your hamster is in what.
anyway, becareful when you look for hamsters ah. dont open or close
door in a hurry cause the hamster might be hiding in between the
gap. and look under your refrigerator as well. my friend's hamster
got stuck under the refrigerator and it got burnt not too
badly.