A: She hasn't gotten enough calcium so the eggshell is too soft to come out.
B: The rooster she is confined with has been too rough with her and has put her vent (where the egg comes out of) out of place.
The hens name is Henrieta, and I was(and still am) very attached to her, so I took her about 3 times a day, and soaked her, from vent down, in warm water for about 10 minutes, or until she started shivering, that means it's definitely time to take her out. (Mind you, I soaked her in a small dark bucket with rubber gloves on, outside, not in the kitchen sink!)
Picture courtesy of the website
Rhymes with Vanilla.
I also separated her from the other bantams, and put some straw in a small round tub with her own food and water. By now her backside is extremely swollen and so there was a lump that came out of her backside, and it was red at first, then it got deeper after a couple days, and then started turning purple. In that lump of skin I could see her vent hole, and her 'messing' hole. Here's a link to google search of egg bound hens.
I covered Henrieta with a towel, so it would be dark and she could relax. I also applied bag balm to her backside. I gave her food and water, and put her where she wouldn't be to disturbed.
Soon, Henrieta layed 2 eggs. The swelling on her backside started turning brighter and getting smaller. Soon, she was a normal hen, so I put her back in with the other two bantams, a rooster and a hen.
Last night I found the rooster, Mr. Rooster, looking very sick, he was licking the inside of his mouth, closing his eyes and keeping them shut, and it seemed he was vomiting a little out of the left corner of his mouth. I put him in a pet crate, and left him in the main chicken coop, this morning when I checked on him, it looked like he had had a stroke, flapped up his wings, and fell on his back and died. I'm not sure why he died, he was only 1 year old when we got him, and I've had him for only about 2 or 3 years.
Also, one reason why I noticed Mr. Rooster, was because the only hen with him was Mrs. Rooster, Henrieta was nowhere to be found. This morning there's still no sign.
It's strange, how a rooster dies after a hen disappears, me and my mother where wondering if he ate something, and she came over and ate it too (whatever 'it' is, I don't know) or something got a hold of Henrieta and Mr. Rooster tried to fight it(again: whatever 'it' is, I don't know). Of course, there would be feathers somewhere if any of our chickens got picked of by a hawk or something. There is a chicken hawk around our place that knows our chickens are loose.
That's a downfall of living on a farm, you see death at certain points, but it's all part of Gods plan, we're born, we live, and someday we'll die.
I hope you have a wonderful fall season!