Prevent father from sale of land

Hello..sir I am Harish My grand father has 6 sons and one daughter,and my father acquired my grandfather property On partition ,my father who is mentally un healthy , and he was not do any work to earn money and food for his family. Or at least him self, my mother get married. At the age of 13, at that time my father going. To agriculture labour work to earn money and food , at that time my father was not do any work for his family, After me and my sister born my mother going to( Kuwait) foreign by leaving me and my sister at her sisters house at that time I was just 4 years old, My father lived at his sisters house who is one of the daughter of my grand father Now they are going to sell my father property by influencing my father. Mentally. And make an agreement from the buyers by taking an advance of 100000 ruppes, and my father. Also signed in that agreement And she was still working at foreign for my education and food , Now I am 23 years old ,how can I prevent my father. From Sale of land? Can I get stay order from couart? If yes then how can I get stay order? Sujjest me sir how can I proceed legally? If Sale is already done?what should I do? Help me sir...please..