Sounds like the back lighting went out on the screen, it is probalby cheaper top buy a new laptop than fix it.
My laptop monitor recently went black while I was working on it. I can barely see the desktop, its there but very dark. Its as if the light went out. I can plug a monitor into the back and the computer works fine. I just cannot use the monitor on the laptop.
Is this something that is going to be expensive to get repaired?

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