I can totally sympathize. We live in an apartment complex and kids come in and out of the house. Because of this, we tend to keep the cats upstairs during the day and release them to the rest of the house at night. However, cats being cats, my (then) kitten Jack had evaded being put upstairs. So a child came over and left the door wide open. We shut the door.
hours later, we realized that we hadn't seen Jack and panic ensued. We thought he'd gotten out and we hadn't noticed...and it's not a friendly environment out there. We looked inside. We looked outside. I was in tears. Bill went in late to work because he spent too long looking. I kept calling and looking. Finally I gave up for a bit.
Much later that night (almost next day) I hear a weird scraping noise in Douglas' room. And there's Jack, dragging himself out through a small opening in the back of an antique radio. He was baffled by my tears and joy...and only barely tolerated being mauled (hugged and kissed) by his wacko human.