I have had friends who have died at young ages.
one committed suicide.
another was killed by his brother.
one fell off a truck head first.
I work in a cemetery and as I go through, row by row, I stop and think about how precious life really is. I see the tombs of my friends and other people I know. I realize that they aren't coming back. But I take refuge in that fact that I knew who these people were and I know without a doubt that they are in a better place now.
Now, I'm a Christian, and I believe God has a plan in everything that he does. Everything happens for a reason. There is something to be learned from every event. I can't vouch for your friend and say that I know where she went. I can't vouch for any of the other ones here. But, the thing about death from a Christian perspective is that it's not permanent. If you and your loved ones believe in Christ, even though one may no longer be in this world, there will always be the future with them to look toward to. Death has lost it sting.
Christianity gives me the best hope, and that's how I move on from the pain.