A single lunged deer may not die. Depends. I am not very good at tracking, so I can't really help you out too much. But...

Do you know the area where the arrow hit the deer? Could the arrow have been deflected? What was the deers reaction to the shot? How far did she run before slowing down/stopping, if she even did? You said there were fawns with her. Did she flee the fawns, or did they stay together?

Stay with it. I hope you find her.