What could be the cause of a monitor not turning on?

Check and. Make sure your monitor cables are securly in , in both the monitor and computer if there is no power to the monitor at all no lights cone in I suggest trying another power cord. If the light is on and is orange it's not receiving a input from your computer could be your video card. Let me know the light on the monitor is turning on.

I had a monitor that was suppose to be plugged into an outlet not a power cord. Dang thing finally quit working so got another one. Worked fine.

Check if the monitor is plugged in or your mnoitor is busted

A its simple
First try checking your power cables etc
Then if it still not works then see that
You don't have busted your ram
If you are connecting it in your 3d card then try to
Connect with theport on your mother board
Thank you.

If you can get your hands on another monitor or have another computer to plug it into then you can narrow down the problem.

After checking all the chords if it still doesn't work try hooking it up to another computer, or try hooking another monitor to your computer. If, when you plug your monitor into another computer, it doesn't work, then you can know that the monitor itself is faulty; on the other hand if it does then its probably the computer. Likewise if you hook another monitor to your computer and it works, then you know it's the other monitor, and if not, then it's the computer.

This is a simple test to narrow down the problem. If it's the monitor you'd be better off getting a new one, than trying to fix it... if it's the computer then its probably salvageable.

If the monitor has never been tested with the computer before then it could be a sync problem, however the monitor usually gives error messages for that.

I'm not a tech, but I agree with infojunkie4life. Also, it could be that the monitor button is loose. Try press and hold for a few minutes. If that doesn't work, then press on and off slowly until the light appears. I just leave mine on after that incident happened to me.