It's worth noting that if you do resort to pushing the company into bankruptcy, at best you'll get nothing, and at worst you'll make things even more difficult for the founders than they already are.
Call them up and tell them straight out that they have a week to get the money otherwise you go after them in court, which will throw the company into banckruptcy.
It's actually possible that no one is getting paid and equity and commitment are driving the ones that are left.
Getting paid isn't just workers, but is also the other businesses.