What to do when neighbour is creating nuisance and illegally blocking?

I have a tenanted portion on ground floor used for commercial purposes since 50 years. Recently my back plot neighbour pulled down an old building and constructed a building for hotel. Both the buildings have a common open air passage for ingress to backside garage which belongs to our building. To beautify the entrance passage he took out the plaster from the exterior of my tenanted portion, removed the Cornish protecting our windows and left exposed to rain for long periods. My interior got damp due to his neglect. Now I want to repair my exterior with damp proofing chemicals and paint it. I presume he would prevent me from doing this as he had stacked up sand bags against my wall. He has also fixed a gate on the common passage which he can block anyday.A police complaint has been made. I do not know the actual owner but it is the contractor who is doing all this mischief. The owner is a Muslim as well as the contractor and it is in park circus area. What steps do I take?