Best way to retrieve the missing knife is to just go ahead and buy a new one... it has happened to me with Swiss army knives more than once.

Three years ago I got fed up with losing expensive pocket knives. I bought 5 serviceable but inexpensive knives from Amazon. I have 4 left in the package. I cannot manage to loose the first one.

I once lost a Benchmade Auto Stryker. Went full-on obsessive looking for it. Finally gave up and ordered another. About three-four months after the replacement arrived, I kicked back in my recliner, and the original knife dropped out of the bottom of the chair.

speaking of this... last Sept. I flew back from Saint Louis and it was raining on the way to airport and so I ended up stuffing my rain gear in the outside pocket of my checked bag... and also realized I still had my swiss army knife on me and so stuffed it in the same pocket.... when I got home the outside pocket was half way unzipped... and the knife was gone.... but rain gear was still there... dern TSA stole it... I am not making any of this up... I left the bag on my couch for the next week and looked in that empty pocket at leas 3 more times... then again when I finally put the bag in the closet.... two months later I'm headed to Front Sight out in Nevada and wanted to see if the new case for my pistols would fit in it and so I pulled it out... and also looked in the outside pocket and there was my knife... either Aliens or the TSA returned it at some point in time... that is the only explanation I can come up with.