What should I do please help here ?

If he is refusing to talk to you and he's happy to talk to other people then I would text him and say that you are assuming the relationship is over based on the fact he won't speak to you and doesn't want to see you. Don't beg or moan. Just be matter of fact and calm. It's a terrible way to treat you after four years. If he sees you are serious he should call you to explain himself. I hate to say it but it does sound like he wants to break up but is just too cowardly to admit it. This or he wants a break and wants to keep you dangling. Don't give him that option. Be assertive. If he doesnt reply to that text then it will be heartbreaking but you'll have your answer and you can move on as he's not worth it.