Sourdough dough collapsed, not rising again... Need help!
This sounds very much like overproofed bread. You should have baked it much sooner, or retarded it in the fridge, not left it on the counter. 

You cannot "rescue" overproofed bread in the sense that the loaf will never have good texture. If you really want to save the ingredients, you can reuse them as a preferment in a new bread. But it is not necessarily worth it, since the overproofing process creates very sharp off-flavors.