MacBook Pro screen frozen with no icons

i have logged into my macbook pro and the macbook works (i clicked in tbe middle of the screen and a youtube video sound played) but it just shows my screen saver with no icons. How do i unfreeze the mac and get the correct display back?

I’ve plugged in a HDMI cable and can access system setting on a monitor but the screen is still empty.

[Re-Titled by Moderator]