Q. My tenants paid one months rent at the time they moved in three months ago but I have had nothing more from them. I have not been able to contact them and the neighbours say that they are not living at the property. I have been round and looked through the windows and all their possessions are there.  

Can I go in and change the locks? They have a one year tenancy.

A. No. If they had moved all their possessions out and left the keys behind that could have been taken as an implied offer to surrender the property (as their actions were inconsistent with an intention to continue with it) and you could have changed the locks. However, you say that they still have all their possessions there, which indicates that they intend to return.