Do you retain copies of bills of lading? One thought, mentioned by another carrier's owner, is to go directly to the shipper to get paid.
Also, you might want to find out if the company owned anything. You can file a small claim in court, but I'd be willing to bet that the company owned little, if anything, that is collectible. Beyond that, you'd have to find out if the owner pierced their own corporate veil by commingling personal and business funds, as it was a corporation. If they did, then you could go after personal assets (money, vehicles, homes). It might take an attorney to do that for you. Not saying that it couldn't be done by you, it's just a lot of homework, for little reward. If I had to guess, you're probably never going to see that money. Again, a guess. If it were me, I'd start making someone's life a living he** until I got paid. Even if I never got paid, I'd do it just on principle. Matter of fact, I have, for a lot less.
Not rubbing salt in your wound, but how did you let this get so far? The only reason I ask is for someone who may be in a similar situation, and can maybe learn from you.
Sorry that you have to go through this much crap for money you've already earned. Hopefully, this can turn into a learning experience for you and others.