I person can not merely claim that company A has gone out of business, transfer all of the assets from Company A to company B for no consideration and then tell his creditors tough luck. Under New York law such a transfer would be considered a fraudulent conveyance and you would be able to pursue any assets that were transferred for no consideration. In addition if Company B is merely a alter ego of Company A or or the owner of the company you may also be able pursue you money this way. In any event I would encourage you to not merely give up on this debt. Contact an attorney that regularly engages in debt collection such as my firm for a consultation.
If the photographer personally assumed the debt, then it wouldn't be true that he isn't responsible to pay the balance, unless he has personally filed bankruptcy. It might be a good idea to consult a local attorney about this.