Partition of great grand father property

Hello Sir, I am Aakash Kumar s/o Lt. Dr. Binoy Kumar. My great grand father has some land property in my village (Birsayar,post-madhubani, bihar) also there is one house which belongs to my deceased grand father. Since, we lived away from the village in the city because my father was practicing his clinic and we never actually lived in the village. So, i don't have the exact information about my property. My great grand father had four son and each of them has 2 son. Out of the four son my grand father was the 2nd son of my great grand father. Now, my grand father has 2 son the eldest one is my father and the youngest one is my uncle. After the death of my father, my uncle is threatening us that he will not allow us to take anything from the property because we never lived there. He is saying that he lived there and took care of the property and he doesn't want to give anything easily to us. My grand mother is sick and she lives with my uncle in the village. she also takes their side. So, i request you to give me some advice about how i can claim my ancestral property. Thank You Aakash Kumar