My grandma had left a house without leaving a will. How to claim legal heirship?

My grandma left a house without leaving a will. My grandpa expired before her. Her only son (no other daughter or son) is my father. He and my mother are also deceased. My brother is the only son and I am the only daughter. My brother has obtained a legal heir certificate without including my name. Now the Tahsildar says I need to go to court and get the legal certificate. In the meanwhile my brother is trying to sell the property. He is residing in the property whereas I am away. We are hindus residing in Tamilnadu. How to proceed now?