It's almost inevitable that I'll not be able to find one item, so I go out and buy another of the same thing. When I get back to the shop, I'll find the original item that I couldn't find within 10 minutes. Can't blame my dog - she doesn't know how to unlock the tool boxes. Can't blame a mischievous spouse - I fired the last one many years ago.
Quite a few years ago, I decided to clean the mechanism in my Herbrand 1/2" drive, 18" ratchet. I very carefully disassembled it, but the detent ball spring decided to escape with a "sproing". I looked everywhere, but couldn't find it. Herbrand went out of business years prior, so I couldn't buy a replacement. OK, I put the cleaned parts in a zip-lock bag and taped the bag to the ratchet handle. 15 years and two moves later, I was cleaning out one of my roll-around tool cabinets when I found a loose spring in a drawer. There was no question as to where it had come from, so I reassembled the ratchet with some good lubricant. That was over 30 years ago, and the ratchet is still with me, and is working perfectly. Since that incident, I make a point of disassembling ratchets and the like inside a large zip-lock bag that manages to contain random escape attempts.