Unregistered sale agreement in Jan 2015

I have entered an sale agreement on jan 2015. For the sale of land. He paid me an advance. We made two original copies. The land belongs to me my mother and my friend. Of equal extent. It is an unregistered sale agreement in that agreement i and my mother signed but my friend didn't sign. Or the agreement which he has no sign of my friend. The other agreement which we have is not signed by the purchaser. We gave possession to develop the land.the agreement validity was four months. It is mentioned that. In agreement that in any case the time will not be extended. But due to mutual understanding we gave him some time and helped to sell the plots to the third parties. The rest land should be registered by him. Since. 5 months we are asking him to get registered but he is ignoring. Now we don't want to sell the remaining land to him Now we want to do marketing to sell the remaining plots. We contacted marketing people they are asking us to get a Noc. From them. Kindly help me in this situation. My email is rakanarya@gmail.com