If the other business was a sole proprietorship, you can sue the owners for the money: in a sole proprietorship, the owner is the business. But if it is was an LLC and corporation, it is a separate entity from the owner(s), and the owner(s) are not liable for its debts. So if it was an LLC or corporation and has closed down, there's no point in suing--there is no one to sue, no one who is liable, and no one who will pay you money.