Get a new one
If your hamster is not breathing, I suspect that he has passed away.
When breathing stops from lack of oxygen
love
its sleeping....
I would call a vet...
If it is like that, cold and not breathing, yes, it is dead.
it means that it is dieing
Dead
It may be excited. Most small animals breath rapidly when they are being held or if you are reaching out for them. It's not bad or contagious but if your hamster is breathing unevenly, bring it to the vet immediately!
Breathing stops for a moment when swallowing. So no breathing occurs when swallowing.
dying
Usually, breathing stops and then the heart stops shortly after.