Futzing with my graphics settings on my Aorus RX 570 card I cleared what I'd been doing. As had happened quite a few times the screens blacked, except this time one of the screens did not come back. While it would have been a lottery winning moment had the monitor chosen that moment to die, I dutifully swapped cables. The monitor that worked no longer does and the monitor that didn't work now displays. FWIW, I did nothing physical with anything other than the keyboard and mouse. I didn't move anything. I didn't change any other settings on the computer. So, either something got miss set, or, the card committed suicide.
Thoughts and suggestions to test stuff would be helpful.