You can hide all open Windows windows in various ways without the Windows key. On a PC, try pressing the shortcut Alt+Tab to hide each window individually, or use the taskbar buttons to hide all open windows at once.
Step
Method 1 of 3: Using the Taskbar to Access the Desktop

Step 1. Right-click the taskbar
This bar is the bar at the bottom of the screen and allows you to access and view programs. Right-click the bar to display a small window with several options.

Step 2. Click the “‘Show the desktop’” option
All open windows will be hidden and the desktop will be shown.

Step 3. Right-click the bar again to display the program window
Look for the option “'Show open windows'” to open or re-show windows of programs that are still active.
Method 2 of 3: Using the “Show Desktop” Button

Step 1. Hover over the right corner of the taskbar
In recent versions of Windows, there's a rectangular button that's hidden in the lower-right corner of the taskbar until you click on it.

Step 2. Click this “hidden” button
The button will appear more clearly once clicked and all currently open windows will be hidden.

Step 3. Show all windows again
If you want to show all previously hidden windows, click the rectangle button. All previously hidden windows will be displayed or re-broadcast on the screen.
Method 3 of 3: Using Keyboard Commands

Step 1. Click the window of the program you want to hide

Step 2. Use the shortcut Alt+Tab to hide the window

Step 3. Click another window to select it
To continue hiding open windows, select each window in order and repeat the command/shortcut Alt+Tab until all windows are hidden.

Step 4. Show hidden windows again with Alt+Tab shortcut
To display previously hidden windows, use the shortcut Alt+Tab before selecting a new window.
Alt+Tab command/shortcut only works to hide/show one window at a time
Tips
- On Mac computers, the shortcut Command+⌥ Option+M hides the currently active window.
- On Mac computers, the shortcut Command+⌥ Option+H hides all windows except the one that is currently active.
- On Mac computers, the Command+⌥ Option+H+M shortcut executes both commands and hides all open/active windows.
- If you are using the Windows operating system via Remote Desktop on a Mac computer, the Alt+⇞ Page Up shortcut will only hide the window on the remote desktop, while the Alt+Tab shortcut only hides the window on the local (host computer) interface.