Dark screen cant adjust

is it dark on picture playback (picture from before fault occurred) and menu also, if not then turn exposure value back up, on my camera you do this by pressing the WB (white balance/exposure button) and turning it to 0. it is the up button on the 4 way knob. but I have a Panasonic FZ20. yours may be different.
If the whole LCD screen is dim, and the viewfinder is OK, then you have a problem with the LCD screen. You will need to take it to the repair agents.