The Librarian

Please may I have your assistance. I am the librarian. I documenter and storer of all things of importance. But there seems to be a flaw in my system. I'm missing a piece, a puzzle piece that I can't find. It would be the key to unlock everything... And, i need you to fill in that piece. Please take this paper and write on it what you wish... It will become a key that unlocks a door. And, through that door, we find salvation... For both of us!