I dont know what happened to my crayfish babies PLEASE HELP!!?

my crayfish had babies and she was just starting to knock them off her tail and i seen a couple of them swimming around at the bottom of the tank. well i walked away and finished what i was doing. i came back about 2 hours later and they all where off her tail but they where all at the bottom of the tank on their backs i didnt think nothing of it because this is my first time having crayfish. so i went to bed the next morning they all where at the bottom of the tank still on thier backs but they are turning red. are they dead? i also have 3 other grown crayfish in there with the mother and babies and 1 of the other grown crayfishes has eggs that hasnt hatch yet please tell what went wrong. are is this suppost to happen. before the other eggs hatch. also i had jus changed the water the day before she started knocking them of. could it be the water was to cold? are it was jus the water change? i dont know PLEASE HELP!!