The company can't pay back the money. What should a salesman do? The salesman didn't sign any contract with the company. Should he take responsibility?

If the company legal person didn't run away, your business people would be fine. This is a typical company's capital chain break, and it can apply for bankruptcy.

If the company absconds with money as a legal person, the victim's appointment procedure is signed by the business personnel, who have certain responsibilities.