Our land forcefully occupied and started construction

I have a land in rupaidiha bazar bahraich district (india- nepal boarder) the land belongs to my late father motilal. I dont have any other legal document ecxept registered patta. Many people in the market in group are forcefully started to construct in my land. I approached nearest police station named adarsh thana rupaidiha. Opposition party has given money to police thana so thana is not acting in our favour. They even dont want to hear us. Then we called dial 100. Dialing 100 relieved us for few days as when police arrive in my land they stopped constructing. When police leaves again they started constructing. Now today when i call dial 100 for help they came and said the document you had is not legal one. You had prepared it in home by forgery. Now we donot have any idea how to stop them from occupying our land. In between this they threatened my family many times and beaten us publicly. For poor people like me there is no any help from administration because they all are sold in money. Even police is not ready to lodge fir against them. Please suggest me what to do next