Uncle refusing to provide papers of property belonging to grandfather

I belong to a hindu brahmin family, my grandfather purchased a plot (6 kattha) in Patna, Bihar. The land was registered on my grandmother's name. My grandmother died in 1997. My grandfather died in 2001. They had 2 children (boys) I.e. my father and his younger brother. A house was constructed on the land during the lifetime of both my grandparents. The house is constructed in approximately 2.5 kattha . We are currently living in this very house. My father (I.e. the elder son of my grand father) died in the year 2007. Since then my uncle ( my father's younger brother) has the custody of the property papers and refuses to even show us the papers. Recently I required the papers for a education loan which he refused to give. We are in a very problematic situation . Please advice us what to do.