If you hunt enough, it will happen again. Even with employing excellent management of tracking skills, having a complete great bow and arrow set-up, competent shooting and excellent shot selection, lost quarry is always a possibility.
For example, an animal may move at the shot.
You may be able to determine if he is wired and wisely decline to shoot and then take a slightly quarting away shot on a calm animal and he turns inside out at the shot. We can't control that.
One of my trophies on the wall was trotting down the ridge broadside from left to right. At the shot, he wheeled and the shot was perfect, however the arrow entered on the left side. I was just blessed that time.
You can never bring that arrow back. Be prepared for the next.