Land right

dear sir,

            I am living in Bihar state . My grandmother was purchase land about 16 dhur(1 dhur= 81 sq ft) in 1980 and she is died in 2000, she was illiterate . My father and his two brother and his one sister were in family. My father was eldest son.Above mention land register with my grandmother name and now currently this land posses by my uncle. Now i want file title suit ,what will be my father share and how much will take to time to solve this matter