I can say I' ve been lucky enough not to lose a deer while bow hunting but I lost a nice buck a few years back on opening day of firearm season. I hit him hard with a 10ga. slug and he dropped in his tracks. He laid there about 15 seconds kicking a little then sprang to his feet and was gone in two bounds. I was dumbfounded. It was fairly late in the afternoon so we gave him about 45min and started tracking. There was enough blood where I hit him that I was amazed he got up. Long story short. I spend 3 long days looking for that deer. I was pretty upset as that was the first deer I had ever lost. Sometimes no matter how bad you want it, it isn' t meant to be. You can' t just give up. Tell you friend that it happens to the best of us. If he' s tuned his bow and did everything possible to insure this wouldn' t happen then he can' t be faulted. It dosn' t make it any easier but this is a time for a bit of fortitude. He' ll be okay just get him back in the woods.