Computer screens, like any component of a computer system, work or fail to work because of a series of possible factors: the input from the computer, the settings on the screen, and the performance of the screen itself. If you are seeing vertical lines on your screen, one of a few things might be happening. Sometimes the fix is simple and straightforward, and other times fixing vertical lines will require some troubleshooting.
Power down the computer and unplug all peripherals. If you are using a laptop, take its battery out by flipping it upside down and sliding the battery release latch. Press and hold the power button for 15 or 20 seconds to clear all residual power from the system. Some of the computer’s power might have been transmitting to the monitor, causing it to short out. Reconnect everything and turn the system back on to see if the lines are gone.
Unplug the monitor from the back of the computer and wait a few seconds until it displays a message “No signal.” If the no signal message also has vertical lines, you know the problem is in the monitor and not in your computer. Press the “Menu” button on the screen and then use the other buttons to browse for a “Factory Settings” mode. Select this mode to reset the monitor to its original settings. If the lines persist, the monitor may have been dropped or exposed to a magnet — which can’t be fixed.
Reconnect and turn the computer back on. Look for the lines at boot up: if you see lines before Windows loads, the problem is either with the video card, the video connection cable — whether HDMI or VGA — or the monitor itself. If the lines only appear in Windows, the problem is a Windows setting — most likely the refresh rate. Right-click on the Desktop once Windows loads and choose “Screen Resolution.” Click “Advanced Settings,” “Monitor,” and then lower the refresh rate to see if the lines disappear.