You need to clean your office and actually come up with a filing system. The geologic approach - where files can be retrieved based on a relationship between time since last accessed and distance down the pile - is not working well. Worse, in your brilliant attempt to outsmart your system, you have inadvertently lost the items you put in a "special" place for the very purpose of NOT losing them. You're getting to be like one of those old people who thinks someone is stealing from them because they put their jewelry in the ice cube tray to hide it, then forget about it, which makes them hide more stuff in a viscous cycle. The time it would take to fix the situation is likely significantly less than the time you spend hunting shit down.