So when you launch the Control Panel, it is opening and appearing on your Taskbar, normally indicating that it is open, with a little line underneath the taskbar icon.
This is just a shot in the dark but perhaps it is actually opening on a second monitor that Windows thinks is there, but for some reason is no longer available.
Try this.....
With only Control Panel open and showing as such on your taskbar, hold the Windows Logo Key on your keyboard and strike the left arrow key on your keyboard four or five times see if that works to bring the Control Panel windows back onto your primary monitor.
If that doesn't work try the same thing only with the right arrow key instead.
As I said "a shot in the dark" but, perhaps worth a try.