My toshiba laptop has a thick white line down the screen
The normal cause of lines across the LCD of a laptop is a damaged video
cable. The unusual cause would be the video card itself.
To determine which item is at fault, you need only attach an external
monitor to your laptop's video-out, and then swap your monitor view to
'both' or mirrored (usually just the function key (FN), plus one of the
Fkeys...look for an off-blue picture of a monitor on the Fkeys).
If the lines across the screen also appear on an external monitor, then the video card is damaged.
If the lines only appear on the laptop's LCD, but not the external
monitor, then just the laptop's internal video cable is damaged.
Hope this helps.