Dispute over Land

Greetings to All,

My question is regarding a dispute between my father and my Uncle (Mother's Brother) regarding a property that belongs to my father.

Back in 1995, my father bought a land in the area of Najafgarh and was soon enough going to start construction of our house. But due to some family issues one of my Uncle needed a large amount of money immediately and so my father handed him the papers of the property to get rid of the situation first and then return the requisite amount later (time and date not mentioned). Later after some years probably in the year 2004, my father asked for the amount that my Uncle had used by selling off that property as my father intended to build property this time. But on a surprise my Uncle refused to pay any amount and even claimed that this scenario never happened. My father brought this in the notice of my Grandfather and my Uncle changed his dialogue (as Grandfather was aware of this thing happening) to "I have already paid him back!" and hence proving my father and accusing him of false allegations. Currently my father holds the paperwork that proves his statement and the land area and the Transferred paperwork to the name of my Uncle. But despite of many warnings my Uncle had never returned the money back to us.
I want to know the correct procedure to sue him in the court of Law as the verbal deal of returning the money back to us later at some point is not mentioned in the papers.
Please advise what can be done and how?
Is it even possible to claim the amount or it will it only end up spending more in the matters of Court upon claiming the amount of that property?

Thanks in Advance