i have a hp laptop, running windows xp home edition. the display is dark, i can barely see anything. I hooked it up to an external monitor and that monitor is displaying it perfectly, i've also tried the other OS's and all appear dark. If someone can please help and save me from ripping out my hair, it would be much appreciated! thanks in advance!!!

try going into the laptop bios and increasing the contrast and brightness

Is it still under warranty? You probably have a bad inverter, the DC-to-AC circuit that drives the fluorescent-tube backlight. Less likely, but possible: the fluorescent-tube backlight iself is broken or disconnected.