Chances are that the file was made hidden. To show hidden files, open up the drive and click "Tools">"Folder Options". Click on the "View" tab. Under "Advanced settings", make sure "Show hidden files and folders" is selected. Click "Apply" and if the files were hidden, they should now appear.
To unhide the files, right click on them and click "Properties." At the bottom you will want to uncheck "Hidden".
Nate, September 2007