TriggerFinger

I assume that the screen was bright and clear when it dimmed out on you. If you are saying that now you can only see the Desktop by using a flashlight, then it could mean you have a defective backlight or inverter.

You can try the advise of SectorCluster to adjust the brightness, but if that does not work for you, the try hooking it up to an external monitor. If everything works fine there, consider replacement of LCD (backlight is part of the LCD assembly) or inverter.

Most often this is the inverter failing but very hard to tell unless you have parts to swap with. I suggest you start with the inverter as this is cheaper and easier to replace. I advise you to seek help from a repair shop if you are not comfortable opening the laptop yourself.