Land encroachment by neighbour

Hi,

Our land is encroached by neighbours and they are not willing to vacate it. They also constructed their house on part of our property and they are not allowing us to step on that property. Is there anything we can do to get our property back? This land is owned by our deceased father. We came to know about the land only few years back.My mother approached the tehsildars office but they are not doing anything about it.

Thanks

Sarika