First, search your rooms, but don't move heavy furniture because if your hamster be underneath it, he could get squashed. Also if you have an model where he would be, like if he ever rolled around surrounded by a hamster ball did he ever head to one room in one, try leaving a treat there to see if he is within there. If he is, first close the door and start looking around and calling his name. However if he doesn't enjoy a special room, put a sort of ladder thing to the top of the cage and over the cage leave a few treats, make certain to have the top open for him to get surrounded by if he does come back.
buy a friendly mouse trap, or recently, my friends hamster escaped and she put a stepladder of books (one stacked on top of the other to make stairs) and put a medium sized bucket by the top of accounts, and put strong scented foods like nuts or bananas, on the top stairs and then inside the bucket too, so after the hamster will simply drop in! remember to put sawdust or bedding at the bottom with some water contained by case its thirsty and so it wont hurt itself when it drops in. do this with going on for 4 buckets to increase the chance of it finding one.
put it near dark places, hamsters similar to warm dark places, so while you have spare time, look surrounded by the nooks and cranny's of the house!
First: search, corners, below sofas, in sofas. Look for poop and other signs of him.
Second: place his cage on the ground and stack books leading up to the entrance so he can capture in. Place little "traps" everywhere. Such as bits of food on tin foil. Bits of peanut butter. Check the traps every now and again, if they are disturbed (bits of food lay around and scattered) Also put flour piles so that if he steps in them you can follow his footprints.
Listen at the floor and walls. If you think you know hes surrounded by a certain room, close off that room and search.
DO NOT move up heavy objects if you think he might be astern them. He might run further under the object to hide and you might squash him. If you believe hes behind your dresser or something, try to coax him out with a treat.
i propose u buy a ratfriendly rat trap(they come as cheap as 5 euro) and place it in the room where he escaped.
if he is control just look real good surrounded by every corner.
and if he did it twice in a row i would consider buying a new pen.
Don't worry. Put a bowl of his food on the floor. He'll eventually get hungary and smell the food. (you may want to put the cage on the floor and the food contained by the cage) My hamster got out a few times and luckily my dogs were outside at the time.