Do you live in the same state as they do/did business? That would make all legal matters *much* less complicated. I'd begin an exhaustive search on the (former?) owner (either an individual or some other legal entity) and try to make contact. The old saying, "you catch more bees with honey than with vinegar" carries more than a little truth.... If no response, than contacting an attorney in that state would be a great starting place.
Do you have cancelled/endorsed payment checks, credit card statements or some other proof of payment? That helps solidify to a judge/magistrate actual financial loss. Also, do you have phone records that detail your attempts to contact them? These are easy to acquire pieces of "evidence" that will help you when/if you retain legal counsel (they will request it anyway - it's good to have it on hand).
Sorry I'm not a better/professional source of info, but the aforementioned is what I would do were I in your situation.
Do you have cancelled/endorsed payment checks, credit card statements or some other proof of payment? That helps solidify to a judge/magistrate actual financial loss. Also, do you have phone records that detail your attempts to contact them? These are easy to acquire pieces of "evidence" that will help you when/if you retain legal counsel (they will request it anyway - it's good to have it on hand).
Sorry I'm not a better/professional source of info, but the aforementioned is what I would do were I in your situation.