I had been away from my home for a while and when I came back and used my computer after a long time I discovered that the power button on the Viewsonic monitor was locked. I was trying to figure out how to unlock it and then voila! Finally something worked out. If your monitor power button gets locked, here’s what you do:
Hold the Button 1 and Down Arrow Button for 10 seconds. It should unlock the Power button. If this does not work or you have some other monitor like HP you can either hold the power button for 30 seconds or maybe try doing a factory reset from the menu.