Lost, as in when a ship is lost, i.e. destroyed or unsalvageable? Or lost, as in irresponsibly misplaced? Is it possible 90% of medieval manuscripts are waiting

Lost, as in when a ship is lost, i.e. destroyed or unsalvageable? Or lost, as in irresponsibly misplaced? Is it possible 90% of medieval manuscripts are waiting next to spare change under someone's couch cushions?