Who can I contact when someone who you were working for sent you american express checks and they were?

counterfeit. I put these checks into my bank account and come to find out a few days later that these checks were counterfeit. These people have contacted me several times since then stating that they would wire the money into my bank account and to date, have not done so. I have emailed them numerous times. Who do I contact to get my money back and make my bank account in the plus again? I really need some help from someone because I am not working as I am going to school and have a son in college who I have been trying to help. Signed, Desperate