please give him following diet regularly, eggs, meet, milk, yeast, fish liver oil, mixed bird seed, monkey chow. and maintain protins, fats, carbhohydrates, vitamins, minerals, water. hamsters love to eat...
Feed an abandoned baby hamster milk mixed with water. The mixture should be room temperature. Hold the hampster in your hand, gently insert an eyedropper with some milk in it's mouth. Allow the hamster to eat.
Take him or her into warm, comfortable shelter. Show it love as you would do with a human baby. Keep in mind this hamster has no mother so you must provide all proper nutrients.