ViewSonic VX2458-MHD No Display on HDMI, VGA, DVI—Possible Causes and Fixes?

I am having a small issue in my viewsonic led monitor VX2458-MHD that nothing appears when I give input to the HDMI port.I read user guide of this model here https://viewsonic.com/me/products/lcd/VX2458-MHD.php, but nothing great found. I also tried VGA and DVI ports, still, the problem is there. What could be the reason? I am confused. If anyone here tells me why this is happening and how do I solve it, I will be thankful.

Is the power cord plugged in? Is is turned on? There should be an LED on or near the power button to indicate that it's on. If that is not lit, then try another power outlet.

When the monitor first powers up, you should see a message on the screen even when no computer is plugged in. If you don't see anything then it is likely that the monitor is bad.

If you see the power-up message but nothing from the computer then you should try different cables (which you say you did) or it could be a setting on your computer.

Nice post, it's there should be an LED on or near the power button to indicate that it’s on. If that is not lit, then try another power outlet.