Lobo, I grieved thoroughly just a year ago, when I figured my son was as good as dead. I will never forget the pain, it was horrible. But looking back now, "I" was the one that caused my own pain, by giving up hope. I had forgotten that our HP has a reason for everything that happens in our lives...lessons to be learned, growth that needs to occur, etc.
Try to take the energy used in grieving and turn it into hope that your daughter will learn, return and that everything will work out exactly as it should.
When RAS got clean, he gave us a thank you card that said "Thank you for not giving up on me even when I had given up on myself....R.I.P. **** the crackhead." It's on my wall and the first thing that I see every morning.
Unfortunately, it's not completely true, since I had given up on him, but that was the lesson that "I" had to learn....there is always hope!
Love, Barb