Reclaim of grandfather land sold by father

Hi, My name is Krishna. Problem: can grandsons reclaim land which was sold by father ( type of property :ancestral property from generations) . In sale deed there was no signature of grandfather. Document was registered in 1976. Only father thumb impression was there. He sold without consent of his son's . At the time of registration sons were minors. So please suggest me is there any chance to reclaim the land and cancellation of sale deed by court.