First off, put some hair or take a piss near your plant. Don't pee ON the plant, but maybe in a circle around it. If there is a hunting shop nearby you could try to get some cougar urine. Hopefully that will scare the deer away, or you could put up a fence, maybe an electric fence.

As to your plant growing back, was it already well into flowering? I don't think it will start flowering until the autumnal equinox, so it's still in vegetative growth. This is a good thing, because you haven't necessarily lost much of your yield. What should happen is that the uppermost node will develop multiple branches, and you will have more than one cola. It may not be as much of a Donkey as you were hoping for, but they may equal a single cola in dry weight. It will probably start growing again really quickly, it may just be a little shocked at the moment. Stay cheerful! Keep it from happening again! :thumbsup: