If you mistakenly deleted “Show Desktop icon” from Quick launch bar on Taskbar. No need to worry you can simply recreate the Show Desktop icon.
Procedure to create Show Desktop icon:
1) Open Notepad.
2) In Notepad type the following text
[Shell]
Command=2
IconFile=explorer.exe,3
[Taskbar]
Command=ToggleDesktop
3) Save the Notepad as Show Desktop.scf. This will create the Show Desktop icon on Desktop.
4) Drag the Show Desktop icon on Quick Launch Bar.