No picture monitor given to me and when hooked up won't come on has no picture

It is uncertain to me that if the monitor is not turning on, with a power light visible or that it comes on and but no picture. My question to you is whch is it? If the power light is on the other question is do you hear sound when you try to play a movie or whatever you use it for? If you have sound that shows me that the monitor is on and working less picture. If this is the case it could mean several things. Some of which dont have anything to do with the monitor but with your settings. Are you using a laptop to hook up to it. If so are you using an HDMI cable connection? The monitor needs to be set to the hdmi input, your laptop might need to be switched to play on the monitor rather than your computer screen by pressing the proper F key. If all of this is correct then I suspect if you have an lcd screen monitor the backlight might have to be replaced. If plasma the plasma light. If it does not have any sound and the settings mentioned above are correct then you have a power supply failure. It could be as simple as a fuse, but in the new electronics the fuse might not look like a fuse most are use to seeing. The glass kind. The new kind are only known to the trained eye. You know you might also make sure whatever you have plugged the unit into has power? surge protector etc. Whatever the case may be plug something else into the same socket just to make sure that works and you know you have power. I do not know your level of understanding so I try to cover it all.