Since I've been very annoyed by the constant popped-up to update to Free Windows 8.1, I searched it up and most people recommended to update to 8.1.
I did, and it was a biggest mistake.
First, the computer wouldn't boot. I couldn't get into safe mode in the normal way so again I had to search up.
After going through the long process getting into safe mode & disabling the display adapter & monitor as suggested, the computer finally could boot normally and got into the windows.
Which brought me to the second problem, I can't control the brightness anymore! It was too bright!! I can't use Fn+F5/F6, I can't use the control brightness from Power Options in control panel! Which I knew because I disabled the display adapter. But when I turned it on, the computer became black screen again.
Please help me on this problem.
Or should I just downgrade to Windows 8 again? If so, please tell me the correct way to do it.
My computer is VAIO E Series.