I discussed the location of the Quick Launch shortcuts in tip 2877.

If you lost your Show Desktop icon, you can re-create it using notepad. Open notepad and copy the following text:

<b>\[Shell\]
Command=2
IconFile=explorer.exe,3
\[Taskbar\]
Command=ToggleDesktop</b>
Save the file as Show Desktop.scf in the "%USERPROFILE%\Application Data\Microsoft\Internet Explorer\Quick Launch" folder.