The laptop screen is dark, what did it?

My sister turned her laptop(eMachines M5405) on this morning, and the screen was almost too dark to see. From about ten feet away, it doesn't even look like its on. She tried adjusting the brightness using the FN and F8 key, but it wouldn't change. The laptop is a few years old, and it has had a few viruses over this year. The internal CPU fan is also broken, so it has an external fan on the back. This is kinda important, since all her school files are on it. Anybody have an idea how the screen went bonkers, or how to fix it?The laptop screen is dark, what did it?
the first thing i would suspect is that the backlight is going bad. if not the backlight it could be the inverter. cant really explain how to fix on here but need to take to computer shop, and i would seriously fix that cpu fan because laptops run hot anyway. may possibly be why the screen is so dim.