My psp screen is too dark

i dropped my psp and now the screen is too dark.the games work,the psp screen dosn't look damaged,ie,cracked or broken.when i turn on the psp the psp boots up ,i can hear sound ,my umd games work but i cant see the picture on the screen ,only very lightly but is not watchable .i try to turn on the brightness button but still the psp screen is too dark.please help i think i have tried everything.maybe the psp screen inside is broken but not sure if i should get a new screen or try and fix it.your help would be very much appreciated.thanks mark.