|Before you Search, first:|
Go into My Computer
and click on the Tools menu
and choose Folder Options.
In there, click on the View Tab
and put a check where it says "Show hidden files and folders"
and UNCHECK "Hide extensions for known file types"
and "Hide protected operating system files".
Then when you do your Search, make sure you check the "Advanced Options" and put a check in the box that reads:
"Search System Folders"
"Search Hidden files and Folders"
Also, don't search for the filename, which may have gotten inadvertently changed, just search for the extension and see what shows up.
And see here: