Check to see if there is a picture on the screen that is faint, use a bright flash light shine at the screen and check if anything is there with it running. If your model has an inverter this is a cheap part that powers the backlight, sometimes they go out. If it has an LED screen, then it is possible the cable or panel is bad or the backlight has burned out, try connecting an external monitor and see if you get any video out from that. If you get nothing from external video out move on.
You can try to remove the ram and put it back in. If that doesn't work, try 1 stick of ram in 1 slot at a time. Move each stick to each slot. A single bad stick of ram could be the problem or a bad slot.
Try to reset the cmos by removing all power sources, battery, power adapter and then the button cell battery from the main board if you can access it.
If it still is not working, you would need to start removing all hardware that is not needed for post, DVD drive, Hard drive, Wireless card, webcam, keyboard, mouse etc, each component can cause problems, this would require a tear down of the machine.