Refuses to talk! Behavior problems

Our done just turned 2 he started to say a couple words when he was little then just stopped. He refuses to talk & would rather not get what he wants than to say something. Occasionally he says something (two word phrase "bye daddy") but then nothing. Everything we tried doesn't work. Now were starting to have behavior issues bc of lack of communication & understanding. Doctors all say he is fine. Any one else with similar experiences?!