Awww there there. My Zebra Nerite that I had received from a friend in Erie died couple days ago. Mine probably died of hunger, though I'm starting to grow some algae since adding more light xD, guess not fast enough. I think yours are probably lost somewhere in your tank, have you tried the FILTER? i found one of mine in the filter one time.
I keep their shells... I tell you don't bleach the shelled, it fades the color -___-
I keep their shells... I tell you don't bleach the shelled, it fades the color -___-