My 3 year old son doesn't talk at all. He just mumbles and he doesn't know how to chose his food. But he loves playing with others and he is a happy ba?

Doesn't talk at all? If your three year old does not talk at all, he is significantly delayed in speech. He needs to be evaluated for a hearing deficit, then by a speech therapist, and possibly a pediatric developmentalist. You should begin this process asap, as the longer you wait the greater the problems will become, and the harder they will be to resolve. Good luck to you.