Landlord damages property after tenant leaves

[Susan Knox]

I have a friend who moved out of a house and left it in great condition, actually better than when he moved in, (I know because I helped them move). The landlord went in after and damaged the property (or someone did) and now he is charging the tenant and not returning the deposit. The tenant took pictures of the house prior to leaving the property. The landlord is a crazy person with mental difficulties.

What can the tenant do about this situation and get his money returned?