1) was it self acquired property of your grand father or ancestral property?
2) if land was held in name of your father and uncle they would be absolute owners of said property .
3) since your uncle has sold his share . your father should sell of the land standing in his name if he needs money .
4) you have no rights on said land unless it is ancestral property .
5) since your uncle has sold 50% of the property ie his share if your father was aggrieved your father should have challenged the sale . the fact that your father did not do so for so many years would go against him in courts .