• Sale of ancestral agricultural land

I have inherited some agricultural. land, a residential plot and a portion in the ancestral house by way of a family partition agreement( not registered) between   my father and his brothers in may, 1982. The property is situated in a town in U.P. My father had donated the agricultural land to one of his younger brothers much against the wishes of my family.My father expired in Nov.  1982.Later on I approached the said brother of my father( my uncle) and it was agreed that he shall pay me a sum of Rs. 24,.000/-as a consideration towards the purchase price of the said land.An agreement to sale was drafted for the purpose of mutual understanding on a stamp paper of Rs.50/- though it was never registered or executed. An advance of Rs. 5000/- was received by me as a token money. A condition was put in the said agreement that the balance amount of Rs. 19,000/- shall be paid to me on or before Dec. 1986 failing which I would be free to take any decision as regards the said property.My uncle failed to pay the balance amount by Dec. 1986.-Q.1 Can I now sell the said agricultural land to any other person? It was also orally agreed that till the entire payment is made my uncle will pay an annual amount of Rs. 20,000/- per annum to me for tilling the land on my behalf. But this money was also never paid to me and the dues have since risen to Rs.6,40,000/-(without interest) while the land is still in possession of my uncle Q.2- Can I now send a legal notice to my uncle for recovery of my dues and getting the land vacated from him and giving it to some other person for tilling.Q.3 Can I now ask my uncle to deduct the token money he has paid to me from the amount of his dues that he owes to me and pay the balance to me.Q.4- what is the legal validity of the said agreement to sale which was drafted for mutual understanding only.The cost of the land has since risen to many lakhs.Since my father and I were in Govt. service we could never pay attention to it. My said uncle has bad intentions about my share in the property and wants to snatch it from me by hook or croook.Please suggest some remedies.