You are in a bit of a mess here, and its entirely due to your own failure to attend to your business.
You need to contact the occupants of the house to establish who is living there. If you cannot call around personally, maybe you can send someone, a friend or employ an agent.
Failing that write to the occupants and ask them to get in contact. But really that is a bit lame.
When you have established contact with the occupants of your property, you can decide if you want to keep them as tenants, if you can come to a satisfactory arrangement with them fine, if not then you will need to explore the position about terminating their occupancy of the property.
How is the rent being paid, who is paying it.