What keyboard shortcuts take me to the desktop if I have no Windows key?

I'm pretty sure that start is the windows key on that particular keyboard, so start+d is likely going to do just what you need.

The accepted answer points out that your keyboard actually does have the WinLogo/Start key.

But if you ever get a keyboard that really doesn't have this key, there's still a way to make such a shortcut.

As suggested here, create a file named Show Desktop.scf (make sure the filename extension is indeed .scf) with the following contents:

[Shell]
Command=2
IconFile=explorer.exe,3
[Taskbar]
Command=ToggleDesktop

Then you can create a shortcut to this file via Right Mouse Click on the file → Send to → Desktop (create shortcut). Then open the shortcut's file properties (Right click → Properties), and on the Shortcut tab give it a Shortcut key by clicking in this field and performing the key combo you want.

I've tested this approach with Ctrl+Alt+D, and it works. One issue though is that the shortcut appears to trigger only after a delay of about two seconds. This is a known problem (with a (weak, but) solution)

If you really don't have the "Windows" key, you can use the "shake the window" technique: grab a window by its title-bar and move it back-and-forth quickly. This will minimize all other windows. Then minimize (or close) the window you shaked.

This is called "aero shake".

To reverse the effect: just shake the same window again (noted by the user IMSoP)! You can even minimise and then restore that window, then shake it, and the other windows will return to their previous state. Restoring any other window will lose the memory of which windows the shake should restore, as it does with Win+D.