You can try a warm, mildly soapy bath to relax her, then keeping her alone in a darkened place for rest. You can try lubricating the egg (as best you can) with most anything slippery like vegetable oil, Vaseline, Preparation H, etc. I'm afraid the prognosis is probably not good, though. You might be tempted to break the egg, but there is certainly a risk the broken shell will cut her. This is one time a vet might be able to resolve the issue surgically and have the chicken survive, though she may not lay afterward.
Good luck.