Start with the simplest fixes first

Most monitors that appear broken are actually just disconnected, powered off, or set to the wrong input. Before you assume the screen itself is damaged, spend five minutes checking the cables and power. A monitor that won't turn on, shows no picture, or displays the wrong input can usually be fixed without opening anything or calling for repair.

The most common culprit is a loose cable — either the power cord at the wall or the video cable running from your computer to the monitor. The second most common is that the monitor is set to display input from a device you are not currently using. The third is that the monitor is powered on but the brightness dial has been turned all the way down, making the screen appear black.

Key Takeaways

  • Check that the power cord is plugged into both the monitor and the wall outlet, and that the outlet itself has power by testing it with another device.
  • Verify the video cable (HDMI, DisplayPort, USB-C, or VGA) is fully inserted into both the monitor and your computer, and that you are not using a damaged cable.
  • Press the monitor's menu button and confirm the input source matches the cable you are using — HDMI 1, HDMI 2, DisplayPort, or USB-C.
  • If the screen is black but the monitor is powered on, turn the brightness dial on the monitor's back or side all the way up.
  • If you see vertical lines, horizontal lines, or discolored patches that do not go away after restarting, the monitor panel itself is likely damaged and cannot be repaired at home.

Check power and cables before anything else

Unplug the monitor's power cord from the wall outlet. Wait ten seconds. Plug it back in firmly — you should hear or feel a small click. Look at the power indicator light on the monitor's front or back. It should be lit (usually white or blue when the monitor is on, or amber when it is in standby). If the light does not come on, the outlet may be dead.

Test the outlet by plugging in a lamp, phone charger, or any other device you know works. If that device powers on, the outlet is fine and the monitor's power cord may be damaged. If the outlet is dead, try a different outlet in another room. If the monitor still will not power on after trying a different outlet, the monitor's internal power supply has likely failed and cannot be repaired at home.

Now check the video cable. This is the cable that carries the picture from your computer to the monitor — it is separate from the power cord. Depending on your monitor and computer, it will be labeled HDMI, DisplayPort, USB-C, or VGA. Unplug this cable from both the monitor and the computer. Look at the connectors on both ends. If any pins are bent, broken, or missing, the cable is damaged and needs to be replaced. If the connectors look intact, plug the cable back in firmly at both ends until you feel it seat completely.

Confirm the monitor is set to the correct input

Monitors can receive video from multiple sources — HDMI 1, HDMI 2, DisplayPort, USB-C, or VGA. If your monitor is powered on but showing a black screen or a "no signal" message, it is probably set to the wrong input. Look for a button labeled "Menu" or "Input" on the monitor's front bezel or back panel. Press it.

A menu will appear on the screen (or on a small display panel if your monitor is very old). Use the arrow buttons next to the menu button to navigate to "Input" or "Source". You will see a list of available inputs. Select the one that matches the cable you plugged in. If you used an HDMI cable, select HDMI 1 or HDMI 2. If you used DisplayPort, select DisplayPort. If you used USB-C, select USB-C. The picture should appear when ready.

If you are not sure which input you used, try each one. The monitor will show "no signal" on inputs that are not connected, and the picture will appear on the correct one. Once you find it, the monitor will usually remember that input the next time you turn it on.

Adjust brightness if the screen appears completely black

If the monitor is powered on (the power light is lit), the cables are connected, and the input is correct, but the screen is completely black, the brightness may be turned all the way down. Look at the back or side of the monitor for a dial or button labeled "Brightness" or showing a sun symbol. Turn the dial clockwise or press the brightness button repeatedly until the screen becomes visible.

If there is no physical brightness dial, press the Menu button and look for a "Brightness" or "Display" option in the settings. Increase the brightness slider to the middle or higher. The picture should appear. If the screen remains black after turning brightness all the way up, the monitor's backlight (the light that illuminates the screen) has likely failed and cannot be repaired at home.

Restart your computer and monitor together

If you have checked power, cables, input, and brightness but the monitor still shows no picture or a distorted picture, restart both devices. Power off your computer completely — do not just put it to sleep. Then unplug the monitor's power cord from the wall and wait ten seconds. Plug the monitor back in and turn on your computer. Wait for your computer to fully boot up and load the desktop.

This clears temporary connection errors between the devices and can fix picture problems that are caused by software rather than hardware. If the picture returns after a restart, the issue is resolved. If the picture does not return, move to the next section.

Identify physical damage that cannot be repaired

If the monitor is powered on, set to the correct input, and the cables are find, but you see vertical lines, horizontal lines, dead pixels (small dark spots that do not change), discolored patches, or a cracked screen, the monitor's display panel is physically damaged. This type of damage cannot be repaired at home and usually requires replacing the entire monitor.

Dead pixels and discolored patches sometimes appear after the monitor has been dropped or bumped. Vertical or horizontal lines usually indicate damage to the internal circuitry that drives the display. A cracked screen is visible as a web of cracks across the glass or plastic front. None of these problems can be fixed by adjusting settings or replacing cables.

If your monitor is still under warranty (usually one to three years from the date of purchase), contact the manufacturer with a photo of the damage. They may replace it for free or at a reduced cost. If the warranty has expired, you will need to purchase a new monitor.

When to replace the monitor instead of repairing it

Monitor repair shops exist but are rare and expensive. The cost to repair a broken backlight, failed power supply, or damaged panel is often 60 to 80 percent of the cost of a new monitor. For this reason, most people replace rather than repair.

If you have worked through all the steps above and the monitor still does not work, or if you see physical damage like cracks or discoloration, purchasing a new monitor is usually the most practical choice. When you buy a replacement, note the size (measured diagonally across the screen in inches), the resolution (1920 × 1080, 2560 × 1440, or similar), and the type of input your computer uses (HDMI, DisplayPort, or USB-C). This information will help you choose a monitor that works with your setup.

Frequently Asked Questions

My monitor shows "no signal" but the cables are plugged in. What should I do?

Press the Menu button and check that the input source matches your cable type. If you used HDMI, make sure HDMI 1 or HDMI 2 is selected, not DisplayPort or USB-C. If the input is already correct, unplug the video cable from both ends, wait five seconds, and plug it back in firmly. If the message persists, try a different video cable if you have one available.

The screen is flickering or showing lines. Can I fix this?

Flickering sometimes stops after a restart. Power off the monitor and computer, wait ten seconds, and turn them back on. If flickering continues, check that the video cable is not bent or kinked, and that it is fully inserted at both ends. If the screen shows permanent vertical or horizontal lines that do not go away after restart, the monitor's internal display driver is damaged and cannot be repaired at home.

One side of the screen is darker than the other. Is this a problem?

Slight uneven brightness across the screen is normal and usually not a defect. If the difference is extreme — one half is nearly black while the other is bright — the backlight may be failing. Try adjusting the brightness setting in the monitor's menu. If the unevenness does not change, the monitor likely needs to be replaced.

My monitor worked fine yesterday but now it will not turn on. What happened?

The power cord may have come loose at the wall or at the monitor. Check both connections and push them in firmly. Test the outlet with another device to confirm it has power. If the outlet is dead, try a different outlet. If the monitor still will not power on after trying multiple outlets, the power supply inside the monitor has failed.

Is it safe to open the monitor and try to fix it myself?

No. Monitors contain capacitors that store electrical charge even after being unplugged. Opening the monitor can result in a serious electrical shock. If the monitor is physically damaged or will not power on after you have checked the cables and outlets, it is safer and more practical to replace it than to attempt internal repair.