why won't my ipod light up anymore?

my ipod turns on and functions as normal all except for it won't light up.
I've tried restoring and resetting my ipod, I've also tried to turn the brightness up on the screen but it's stays dark.
I can only see whats on the screen if it's in sunlight or undeher a light source otr wise it's too dark to see...
why is this happening and can it be fixed?