Of all the things I have lost in my life, I miss my mind the most! I am forever losing things. Bought a really expensive pair of scissors at a quilt show. They sat in my living room still in the package for months. Then they just disappeared! My DH swears he doesn't remember seeing them. I am pretty good about the feet for my machine because I am fortunate enough to have a sewing cabinet and I keep my feet in the little drawer. Walking foot always goes back in the box after using then back in the drawer. I don't even have to get up to do it. So in that respect I am ok (I am sure I have now jinxed myself!)
I sure hope your foot turns up.