What do I need to do in order to establish my right to my parents' property?

My mother was the owner of the property. There is a deed of the land that was purchased in my mother's name, and I have gotten a copy of it with the help of a lawyer. She died at home on October 29, 1973. My father died on October 14, 1986. At the time of my mother's death, she left three surviving children : (1) my elder brother, Subhabrata; (2) my elder sister, Monika; and (3) myself, Gan, the youngest son. In 2010, my elder sister Monika gave away her 1/3 share of the property equally to Subhabrata and Gan by a Dan Patra, that was registered in the Burdwan District Court. As far as I know, there is no Porcha of the property at the BLRO office. My elder brother, Subhabrata, does not want to talk to me regarding the property, and does not want to show me the property records that he has. In fact, he does not want me to get into the property. I (Gan) have been living abroad since 1971, and have recently come back to India, and have been living in a separate home. How do I get my property right and possession back to my parents' property?