I deserve to be laughed at for this one.
I was building a desk (from a kit) for my brand spanking new home office, and was devastated to discover a critical base part missing. There were supposed to be two and I could only find one. Several emails and complaint forms later, the company agreed to ship it to me, wherein it got held up in customs for a week while my poor half built desk languished and I continued giving myself wrist problems on the makeshift setup.
The piece finally arrived today. You probably see this coming, but as I was installing it and looking for the next parts, I discovered the piece I'd been missing all along, sitting under the box.
At the very best, I'm a dumbass.