Share in ancestor's property

Hello, My great grandfather got agricultural land from his mother-in-law before independence, he had 2 sons (one is my grandfather and another one is his elder brother) and 2 daughters, and he divided that land as two equal shares and gave it to his sons. My grandfather is having 2 sons and 2 daughters. Later in 1985 my grandfather, my dad and my uncle (dad’s brother) all together sold half of our property to my grandfather’s brother. The remaining part of our land was given to my grandfather for his food needs, he expired in 2010 till then he was with my uncle (my dad’s brother). During his life time he wrote a will stating that the remaining property has to go to my uncle’s son since they taken care him during his life time. My dad expired in 1990. My mother and I approached my uncle to ask our share in that property but my uncle is not ready to give my share in ancestor’s property. Could you please tell me, is that will is valid? And how to get our share in that property ?