Land sell without my notice

You are assuming that all transactions are verbally.  To my expectation and experience, your uncle is very smart and he had sold the property to the present owner without your consent.  Instead of assuming, you better go to the concerned sub registrar and make search of your property.  It is time consuming and money consuming, but not impossible.  Your father might had given written GPA to your uncle, otherwise the present owner will not dare enough to stop you for making constructions.  First of all you do the following:  (1) check up E.C. from 1983 to today, the details of property of 1983 document should be entered  (2) Ask the present owner to show his documents and check up what is the connection between him and your uncle.  After making all the enquiries you revert me to my email id ravinder2345@gmail.com.  I will clarify your doubts.