We are friends for last 8 months, we used to chat and call 24/7 through phone, we wer close, but suddenly 4 days back he started reducing calls and avoiding me. What is reason? What should I do?

He is friend of yours right, so put that question straight to him. There could be many reasons, like he is really busy etc. Let us see what he answers or how he behaves to your question.

We can't read his mind. Easy way to find out is to ask him.

Ask him what's going on. Then you will know.