Attack! Marketing I have not been paid for a job I did 6 months ago. Los Angeles Nationwide

I did demos at grocery stores for a company called Surya Brasil through a promotional company called Attack! Marketing. I finished my last demo in August. I was told that once I sent all of my supplies back to the supplier (which I did) that I will be paid my final payment. This was in August. It is now December and I still have not been paid. I have tried to get in contact with somebody at this company for months with no response. Now, their phone number has been disconnected and nobody will respond to my emails. Apparently their office is now for rent so I am not sure if they went bankrupt. Please help!