It is easy to get nervous about their no eating, but they have a yolk sac that reabsorbed into the abdomen just after they hatched. If you look at the plastron (underside), you can see the spot that closed up (equivalent to your belly button). Did you also notice the tiny, white speck on the very front of the mouth? That is the egg tooth that they use to cut through the egg shell. Same kind of thing found in birds. It will fall off within the first week.
If, after the first week, you want to stimulate them to start eating, look for small, live foods at pet shops. Moving prey are hard for the little guys to resist. I get mine by using a fine net in a local marsh and pull out insect larvae, gammarus and aquatic worms. Pet shops may carry Enchytra worms, tubifex worms, or brine shrimp. Very small earthworms work well, too. Once they start eating, there's no stopping them and will beg for food incessantly. Be careful in feeding turtles, especially young ones. If they are overfed, they can develop deformed shells, including what is called pyramiding. Feeding once a day is sufficient and some recommend a day of fasting each week. Between feedings with high protein foods, just place a leaf of dark-green Romaine lettuce in the tank. They will enjoy it and you'll not overfeed them.
