hi mate, it all depends how old your cuttings are, if there only a day or two old, then cut a fresh slice about 1/4 of a inch from the original cut,and soak heaverly in fresh water, have they dried out as a result of not watering them, or to much heat, or when you took the cuttings was they left to stand for a while out of water, if thats the case its possible that they have taken a air blockage, so making that cut is your only option,
i feel ya pain mate but i need a little more info to be able to help, what are they growing in, and what is there inviroment like, how old are they, and have they started to root, let us know mate it might be poss to save them.
peace ..................... happy ....................