I'm so sorry, but it was probably best for the chick. I had to do the same with two of my birds recently as they had problems and I had to cull them. But the rest of my flock is lots happier and it was best for me and the rest of the flock. Good Luck with the others and future birds!
I would dip it's beak in the water and see if it reacts and starts drinking and for food I would get something mushy instead of real chick food for now as it may be easier to eat for the chick.