I must disagree with the "look until you find her" theory. I could make an argument for "look until the meat would be spoiled" but even that's a stretch.
There's no sense in looking for a dead deer 2 or 3 days. It could be 4 counties away by that time. If you hunt areas anything like I do, it could be on posted property (the kind where you have ZERO chance of access) in as little 50, 100 maybe 300 or 400 yards in any given direction.
No sense in losing sleep over it either, unless you did it on purpose. It's going to happen sooner or later. This isn't like shooting a person. If inflicting pain is immoral, shooting them is immoral. It's the intent that counts. If you did your best and did a reasonable search, and I do mean reasonable, not 5 minutes and not 5 days, then sleep well. You did your best.
Yes, it sucks, but you didn't hurt Walt Disney's Bambi. You hurt a real deer. It's not afraid of death, of what waits on the other side. It's family is not worrying about if it will be OK, or where it might have gone if it's dead. They're not crying over the loss or sharing fond memories.
Live and learn but sometimes there's not much to be learned. Aim a little higher, maybe? But you don't want to hit too high either.
I had a similar situation a couple years ago. 40 yards, standing, broadside, I was sitting in a chair, elbows on my knees. I've made freehand shots and twice that distance with the same gun. All we found was a piece of meat/bone and 3 specks of blood.
It happens. It's hunting. Life goes on.