Why is there a vertical multicolored line on my lg pc monitor?

"@dominick2000

if it is a single pixel thick line it is most likely a bad TAB. You can try and exert some pressure on the small ribbon cable that enters the LCD. If that line changes it is a failed TAB. That would require a replacement of the display since failed TAB’s require special machinery to repair."

This could be a problem in the display or the computer video adapter. Try changing the resolution settings for the display and change to 800 x 600 and see if the vertical line changes or disappears, when you change resolution Windows shows a preview of the change and will automatically revert to previous setting unless you choose to keep the setting. Another thing to try is update the driver for the video adapter. If the problem persists then the issue is the display itself.