DS now 5 all last year and all this year would tell me he didn't know what he did at school all day. I couldn't get anything out of him unless I knew from his teacher what had happened and then would ask him and he would confirm it. Just recently I've found a trick that works with him to get him to tell me about his day. When I pick him up after he's settled in I excitedly tell him in detail about everything I did while he was away at school. Then I ask him what he did and he tells me! Now once he's in the car he's to the point that he asks me what I did while he was gone and I tell him and then he shares his day with me.
I hope you find a way to get him to talk. Just hang in there and keep trying.
