REPOST THIS = EMERGENCIES, DISEASE, INJURY & CURES forum also, you may get better response.
You have 3 eggs that are 20day into incubation, hen crushed her eggs with on out of the shell. Are all the eggs "crushed"? A picture would help to determine how badly. I'm no expert, just a "what I would do, knowing what I know" - I'd remove all the eggs & on a tray that's lined with a towel or paper towel (keep damp) under a heating pad & covered keeping it warm (99 degrees). The one that's out of the shell, assuming it hasn't absorbed all the yolk yet see if you can put (whatever's connected) in a tray lined with a towel/paper towel that you can keep damp and again under a heat pad or lamp. The eggs should have started pipping day 21, thinking this a first time for Mama hen she heard the peeps/pipping got curious. Hopefully all will complete the hatch, dry up & you can stick them under her at night when she's in the nest box or early before she wakes, best chances of her accepting them as hers. Good luck
But like I said, this is what I'd do & don't have the experience in hatching like others do. Try reposting in the above forum also, may get faster response.
I don't know what went wrong this morning, I have gone out to discover that my Mama hen has crushed her 3 day 20 eggs shells...one was out and is barely alive, she keeps getting up off them. I have done nothing to bother her in the past 3.5 weeks other than food and water given to her. She is in a nice secluded brooder box and was doing great. I can see movement in the other 2 shells, so there is life. What to do now? It is my first time allowing a Mama hen to raise them from eggs being hatched. 
