External display

UPDATE: Eventually the "Un-plug, re-plug" failed with all the movement of the laptop off the desk, shutting down etc. so I needed further investigation. I think I have now come across the fix. Somebody had posted a Display setting that seems to overcome the problem. My setup is MBP Pro 14" on the desk, two HP monitors as external displays. Ensure both external monitors are connected, one maybe blank!! but recognised in the Display setting window. Now select Built-in Display (MBP), and make sure that Use as .... Main Display.... More Space" is selected. Now the blank display activates !

I upgraded to Ventura last night. This morning, Samsung external display not working. Had worked perfectly for months until now. USB-C Cable is providing power but no video. Display knows there is something connected and is asking me to 'turn on the device connected to USB-C'. That device, an almost brand-new M2 MacBook Air, is, obviously, already on. 

I've rebooted MBA and monitor, then restarted MBA in Safe Mode. Hasn't worked. 

Displays options - shows monitor as Airplay option but not as external monitor via USB-C. Holding Option key reveals 'detect displays' button, but clicking said button does nothing. 

Following call to Apple support I also created and tried using another user account on the machine. Didn't work.

My Sony external display (the only display connected to my mac mini) comes up with the dock and menu bars off the screen after upgrading to Ventura.

I can adjust the overscan to scale the screen down - but the overscan setting is not saved, so I have to adjust it each time I log in.

I never had to do this with previous versions of MacOS. I suspect some resolutions are missing from Ventura.

Same happened to me with 16.1 I have two external HP monitors, all worked fine with initial Ventura upgrade, now only 1 monitor comes on with my MBP, as well as the MBP screen. Display panel in System Settings shows all 3 displays, I can move a window into the black display, so it knows it is there??. Swapping around cables (USB-C to HDMI), and different ports on MBP makes no difference.

You Know Sam, don't be embarrassed, I disconnected the suspect dead monitor and connected an old 'third' Dell monitor to check that my MBP wasn't this issue. I was about to return the dead monitor to where I had purchsed it, and for some reason decided to give it one last try. You guessed the result!!!! Go figure?

Another old chestnut…… I had turned the screen off at the button and unpluggged the power cord several times before, but it was only when it had been disconnected for a longer period that it recovered when powered up again.

I'm embarrassed to admit this, and embarrassed to suggest it as a solution, but unplugging my monitor and powering it up again fixed the issue.

Alright, that's great. Good to know that the time-honoured "turn it off and back on again" still has a role to play :-)