Gain back possession of my property

I use an estate agent to manage my tenants, however the tenant I had was issued a section 8 and 21, they have moved out a few months ago but I have been refused possession from the courts now and the tenant will not hand over the keys. What is my next step?
The tenant has damaged my house, removed my carpets and electrical goods, run up a substantial amount of debt with the gas and is in rent arrears.
Please help as I want to get my property back ASAP