Question Blue vertical lines covering most of my monitor

I guess try the easy things first. Change cable. Test on another system.

Worst case the graphics card is dead.
 
Check the video cable on both ends. Make sure it's secure. Make sure the connector receptacle isn't loose.
Try a new cable.
Try the monitor on a different computer.
Lightly pinch the bezel (thumb on bezel front fingers on monitor back) all around the edges of the monitor to see if the visual issue changes in any way.