As you probably read, I'm dealing with the same thing. Our hen is all skin and bones, and yet I've been trying to get her to eat expensive and exotic grains like amaranth and she won't eat it!!!!
I've been "force" feeding our hen, putting food on the end of her beak and giving her water with a dropper. (I've seen some people put a tube down their hen's throat and pour stuff down, but I don't have the guts to do that.)
Just get something- her regular feed, exotic food, anything! in her if she's not lethargic or having crop issues. Also, if you perhaps have Nutri-Drench on hand, you should give your gal some of that. If not, any chicken electrolytes will help her.
Not to make this gross or anything, but did your hen have an egg stuck in there (egg bound) or... ???