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I really need help. I have Kubuntu 16.10 on my laptop a everything worked. With external hdmi monitor too. But once I unplugged the monitor, then plugged it in again. And now it doesn't work without the external monitor. After login I have only black screen. Any ideas?

marked as duplicate by Pilot6, Zanna, Jens Erat, Eric Carvalho, amc Nov 18 '16 at 5:50

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To fix the keys not changing brightness Modify the file in here /etc/default/grub as mentioned here. enter link description here.

Good luck.

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