Oh dear Lee sorry to hear about your hamster.
A similar thing happened to mine when I was little. The liitle mite was cold and stiff but I sat and held him in front of the fire and eventually he warmed up and came to life again.
Unfortunatly the 3rd time it happened he wasn't revivable
On a similar note I also revived my goldfish a few times. They lived for many years in the end but until they finally croaked it I found that plunging them in bowls of ice cold water followed my warm water then ice cold water etc gave them a bit of a kick into living again
