Sounds like your mantid got stuck, as the molting process itself usually only takes 15 minutes to an hour once started. They have to dry 24hours or so for their new exoskeleton to get hard, as until then it is very soft and any efforts by anyone will literately rip them. If they fall or don't have enough room there can be lots of damage to them, and in nearly any instances I had they had to be placed in the freezer. A few that did survive had various problems.
Is he still in the old shed skin when he fell? Is it an adult with wings or just a nymph still? is it in a "pile" and unable to move? Any photo would help.
