|If it's there all the time, it probably can't be anything other than the LCD display's circuits are damaged. Driver problems don't cause single lines.|
You could try connecting a monitor to your VGA port, but it's likely the video on that will be fine.
See response 1:
See your Owner's or User's manual for your model to see if there is a key or key combo you need to press to enable the VGA port to enable a display.
E.g. I found this on the web....
"On Toshiba laptops you can toggle between internal and external screens using Fn+F5 keys. Hold down Fn and press on F5 until you get video on the external monitor.
On IBM laptops use Fn+F7.
On HP laptops use Fn+F4.
It’s possible that you have to use a different key combination on your laptop but you get the idea.
On some laptops, in order to be able to use the external monitor, you have to connect it to the laptop and then restart the laptop so the external monitor is detected by the laptop."
NOTE - monitor video cables are NOT "hot-pluggable". DO NOT unplug them or plug them in while the computer is running !