Hello, my laptop screen won't display anything. It boots up and displays perfectly through an hdmi and my T.V.. I can't adjust my screen brightness either, nothing comes up when I use the brightness function keys, the other function keys work fine. I went to device manager and everything under Monitor and Human Interface are updated. Under Monitor the device is Generic PnP. I'm on an Asus laptop, Windows 8, 64 bit. I'd appreciate any advice.
Had this same issue with a Lenovo T420 laptop; I cracked the screen and when I used the VGA cable to connect to an external monitor it just showed black.
: The monitor will display the Windows (or OS) logo until it boots into the OS because during the boot the motherboard displays output to the second monitor however once the OS is loaded the computer switches to Extended Display allowing the user to use both monitors (If they both worked)
: I was able to get the laptop to display only to the monitor when connected by:
1. Turn off computer completely
2. Connect the VGA cable to the laptop (output) and monitor (input)
3. Power on laptop and Immediately close the cover of the laptop completely shut
By doing these steps the BIOS will boot recognizing the monitor as the main and only output option allowing
the monitor to continue to work even after loading the OS (ie. Windows 8)
The laptop will be completely closed therefore you will need a usb or bluetooth keyboard and mouse in order to perform operations going forward
hope this helps