What Do I Feed A Newborn Hamster Who Has No Mother?

Geez... Not a good day I'm guessing!
If it's still a pinky (no fur, eyes closed), which I'm assuming it is, it's chances are very, very slim, and if it doesn't make it you should feel like you should have done something more, it's just a very fragile little thing that isn't intended to survive with out it's mother's constant care and attention.
You can try going to the pet store and getting a can of puppy formula and feed it every 2-3 hours with a eye dropper, just a drop or two.. Just 'til his belly rounds out and is full... Once he stops lapping, take it away.  After each feeding you you'll have to stimulate each pup to urinate and defecate,  just like the mom would do... Gently rub its urethral and then anal areas with a warm, moist tissue or Q-tip... Until it goes (should do it right away)

When you feed it with the eyedropper be very careful and to do it gently never forcing the fluid because it's real easy for a pup to inhale the fluid into it's lungs, and if that happens it just won't make it.