We have a property(A power-loom shed), which has been rented out to a tenant since past 20 years. R

We have a property(A power-loom shed), which has been rented out to a tenant since past 20 years. Recently we have been trying to get the property vacated. We tried to talk to the tenant to vacate the property. We offered him some settlement which is usually done in the city. He didn't agree to anything which we offered. He included a lot of intermediaries, but he didn't take the advice of any of these intermediate parties. During this period, the we came to know that the power supply company had disconnected the power supply to that property and had sued the person who was running the power looms.

This event brought a few more things to light. We came to know that our tenant has rented out our property to another person(This person had possession to the property currently). We had been continuously trying to settle things with our tenant, but he was not at all coming to terms with us. So, we tried to get possession of the property to put pressure on the tenant so that he reaches into some settlement. So, we gave some money to the person who had possession of the property currently and get the keys to the property. So, the current status is that we have possession of the property , but still the settlement is not being done. The tenant is not coming to terms with us. What are the suggestions to me, how should i proceed on this?