Diamond Sword Gone/Disappeared

Had a diamond sword enchanted with Knockback II, Fire Aspect II, and Sharpness III. Added an enchanted book to it (Looting III). Then added another enchanted book to it (Sharpness III). The sword had Knockback II, Fire Aspect II, Sharpness IV, and Looting III. I put it away in one of my chests, exited the chest, then exited the game. Upon logging back into the game, the sword was gone! I would very much like to get this sword back as it took a while to get and is a very good sword, thank you.