I can't tell you how many times I've lost a piece of a model in my 'model room'! Fortunately I have a broom and a dustpan. If I search (sweep the floor) long enough I usually find the part I'm looking for. Hardly ever fails, so that any more if something is missing I just get the broom out, without thinking, and start sweeping. Sure enough it'll show up. Sorta of an opposite to Murphy's Law.
Glenn