This particular fault usually is a result of a bad connection between all the interface boards (integral to the LCD panel assembly and not replaceable) and the LCD matrix itself. There are a whole bunch of adhesive-made connections along the LCD edge. If one of these connections fails, you'll often get a line like this.
Tap GENTLY on the screen bezel at both ends of the line. If the line flickers with your tapping, this confirms this fault. You can try to GENTLY bend the panel a little to make the connection work again. It doesn't take much. Which way you have to bend it depends on what happened, so you just have to play around. This is a LAST RESORT as you're just as likely to make things way worse.