Backlight does not work

I have a Sony Vaio Vpceh40eb/W laptop, all of a sudden it's backlight stop working , i still use it with an external monitor ( I'm writing this using it )

I am preety sure that it is just the backlight because when I shine it with a very powerful light i can see what is on the screen.

Help me guys, is buying a new screen the unique solution? ( is that even a solution?, could it be that there is something else that is not in the screen causing the problem? )

Thanks a lot