To verify if it is only a back light or some thing else, turn on the monitor with the pc running so that you would expect to see a picture. With the lights in the room off (room darkened) place a lit flashlight up to the monitor an see if you can any image on the screen, if you can see colors and images then it is the back lights or more likely their controller board. If it is pitch black with no color or movement then it isn't the lights. If the power light comes on and blinks and either continues or goes out, you are probably a victim of faulty electrolytic capacitors. Many monitors and tv's have fallen to this over the last 5 or so years. They are substandard parts that have infiltrated the supply line in the last 10 years. If you know how to solder on a pc board they can be replaced for pennies, if not and it's out of warranty then take it to the ecycle yard and buy a new one.