What we did when we lost one of ours is get a container that hammie can get into e.g. shallow storage box/bucket but cannot climb out of again. Put loads of food in it make steps up to it with books,magazines or anything to make a ladder to top of container.
Hamsters normally run round edge of rooms so put near edge of room. probably wont come out until all is quiet at night so dont panic if you dont see hammie.
Put some bedding in container so hammie can have a sleep after its adventure. This trick has never failed with us and always found hammie in container in the morning.Ps take the cage away as she will sneek back and eat and will then be off partying again if she can get back out of her cage.
Hope this works for you and Jessie