How get back the plot post the agreeable time period

I had purchased a plot in 1991 from a firm of real estate which has a land of two adjoining villages, belong to different districts of a state. Firm was execute a sale deed of share (8M) from land of one village and firm gave a possession of the plot. At the time of possession i did not know the said plot falls either fully or partially in other village land. About 8 years later(1999) ,Firm was dissolved and one of the partner of the firm, who have share of land (Roads and parks) in other village, had disposed my possession and told its not your plot, then said plot is sold to other one.

To get back the plot what do we need to do?