Never give up! It is a matter of principle for me. I have gone as far as droppng something else in the same area where I was working to see if I could tell where a small part went. It comes from being in aviation where a missing tool or small part can end up causing expensive or deadly problems. Use telescoping magnets, balled up tape on the end of a flexible wand, coat hangars bent in impossible shapes, hooks made from .032" stainless wire, compressed air blasts to move a lost object you can't see to a place where you can (sometimes I've heard it move after a blast and voila!). I don't do it often, but if I find myself doing a job where I have a bad memory of dropping something, I'll tie a string to it. It has saved me much effort on more than one occasion. I have a collection of small parts that others have lost over the years. Most of the items are washers, nuts, and cotter pins.