They might have dried out or had pathogens in the tank ( Frank said that kills some during hibernation / brumation)..personally, I would dig them all up, place in a dechlorinated water dish, offer food in a seperate feeding tub, so theres no feeder insects rotting in the tank, also put a layer of damp (moist, not wet peat moss on top of what you have already in there - and after they have an hour or so to eat if desired, in a seperate feeding tub, and a manditory sit in water dish, then let them rebury themselves in slightly moist peet moss - its acid level cuts down on pathogens. Remove heat lamp and remove under tank heaters if you have one in there. Heat dries them out and can kill them...to eliminate the possibility of other toads drying out and dying from dessication, I would do this, just to be safe. Better safe than sorry. No heat soueces, and make sure they get a chance to soak, and add an inch or two of slightly moist peet moss, both for moisture and to e
Reduce pathogens.