Disconnect all cables from the monitor. Hold the power button down for 30 seconds. (Power drain) reconnect and reseat the connections, ensure your monitor and setup is plugged into a surge protector/grounded circuit. If that doesn't rectify the issue, your monitor went out. Get a new one.
Screen and aspect ratio in windows and drivers is not the issue, from the screenshots I'm seeing. unless it happens to every monitor you connect to. Then you got a whole new slew of problems we need to troubleshoot.