Remedy in case Ancestral Property taken away by fraud by uncle

Hello. My grandfather were two brothers, my grandfather has only son my father, and other grandfather has two sons. When both grandfather died. The property (11-Bigaha) was divided as half (5 1/2 Bigaha) under my fathers name and other half (51/2 Bigaha) between both of my uncle. One of my uncle is running educational institution, and when he require money or property to be shown under his name for opening degree college he has asked my dad for 8 manda, but by fraud he has taken all our property signed by my father who doent even know how to read hindi properly My dad is so innocent that we came to know about this after 8 years, due to some issue between both of my uncle. Now can anyone suggest how to proceed, as now everyone is in deep depression with this incident and every time when we ask uncle to return our property he again and again ask's for few month duration and escapes. Please suggest because all our happiness is gone and left out with nothing. Thank you in advance.Hindu