Yea that's sad, I hope I don't run into that situation. This year is my first year bow hunting. I've hunted 8 years gun and have always had my deer go down within 80 yards and never needed a second shot. This year though bow hunting opening week I took my first shot at a smaller buck with my bow and hit it.
Found a blood trail 20 yards away that started, I fallowed it for an hour in a half through real thick brush and prickers until it came to an end. There was a big circle of blood and it just ended. My dad and I spent over 5 hours searching and searching, but never found the blood trail continue along with not finding the deer or my arrow. I was bummed for this was my first experience like this. We tried all we could. I thought that was bad but I hope that situation doesn't happen again or one like yours.
As Ted Nugent says, all you can do is try your best and make the best shot you can as well as try hard to find the deer and sometimes a weird situation will come up and you can't beat yourself up over it.
Good luck the rest of the season guys!