A black monitor usually means the cable is loose, the input is wrong, or the computer stopped sending a signal

A completely black screen with no light at all is different from a screen that lights up but shows nothing. Start by checking whether the monitor itself is powered on — look for a small light on the front or back of the monitor. If there is no light, plug the power cable firmly into both the monitor and the wall outlet, or try a different outlet to rule out a tripped breaker.

If the monitor has power but the screen is black, the problem is almost always that the computer is not sending a picture to it. This happens because the cable connecting them is loose, because the computer is using a different output port, or because the computer itself has stopped working. You can narrow this down in a few minutes by checking each connection in order.

Key Takeaways

  • Check that the monitor power cable is plugged in and the monitor itself is turned on — look for a small light on the device.
  • Unplug and reseat the video cable at both the monitor and the computer, because loose connections are the most common cause.
  • If you have multiple video ports on your computer, try plugging the cable into a different port, since the computer may be using one you did not expect.
  • Restart your computer while the monitor is plugged in and powered on, because sometimes the computer stops sending a signal and needs to be rebooted.
  • If the monitor shows a "no signal" message or a menu, the monitor itself is working and the problem is with the computer or cable.

Check the video cable connection at both ends

The cable running from your computer to the monitor is the most common culprit. Even a cable that looks plugged in may be loose enough to break the connection. Unplug the cable from the back of the monitor, wait a few seconds, and plug it back in firmly until you hear or feel a click. Do the same at the computer end — unplug it from the port on the back or side of the computer tower or laptop, then plug it back in.

If the cable has a connector with small pins or holes, look closely to make sure none of the pins are bent or broken. A bent pin will not make contact even if the cable looks plugged in. If you see a damaged pin, you will need a replacement cable — they are inexpensive and available at any electronics store or online.

Try a different video port on your computer

Most computers have more than one video port on the back. Common types include HDMI (a flat rectangular port), DisplayPort (similar to HDMI but slightly different shape), DVI (a port with two rows of small holes), and VGA (a port with three rows of small holes and usually two small screws). Your computer may have two or three of these ports, and it may be using a different one than the one your cable is plugged into.

Unplug your cable and try plugging it into a different video port on the computer. If the monitor lights up, you have found the active port — use that one from now on. If you have a laptop, check whether it has a video port at all; some laptops only output video through USB-C or Thunderbolt, which look like small oval ports. If your monitor cable does not match any port on your laptop, you may need an adapter.

Restart your computer while the monitor is on

Sometimes the computer stops sending a video signal even though it is running. Restarting the computer often fixes this. Make sure the monitor is powered on and the cable is connected, then restart your computer using the power button or the restart option in the operating system. Watch the monitor during the restart — you should see the computer's startup screen appear, even if the desktop does not show up afterward.

If you see the startup screen or any text appear on the monitor during restart, the monitor and cable are working. The problem is then with the operating system or graphics driver, which may require a different fix. If the screen stays black throughout the entire restart, move to the next section.

Look for a "no signal" message or on-screen menu

Some monitors display a message like "No Signal" or "No Input" when they are powered on but not receiving a picture from the computer. If you see this message, the monitor itself is working correctly — the problem is definitely with the cable, the port, or the computer. This is actually good news, because it narrows down where to look.

If the monitor shows an on-screen menu (usually accessed by pressing buttons on the front of the monitor), you can use it to check which input the monitor is listening to. Look for a button labeled "Input" or "Source" and press it to see a list of available inputs. Make sure the monitor is set to the same input type as the cable you are using — for example, if your cable is HDMI, the monitor should be set to HDMI input, not DVI or VGA.

Test with a different cable or monitor if you have one

If you have access to another video cable or another monitor, you can use it to figure out which part is broken. If you have a spare HDMI or DisplayPort cable, try it in place of the one you have been using. If a different cable makes the picture appear, your original cable is damaged and needs to be replaced.

If you have access to another monitor, plug your cable into it instead. If the picture appears on the second monitor, your original monitor is broken. If the picture does not appear on the second monitor either, the problem is with your computer or the cable, not the monitor. In that case, the computer itself may need service or troubleshooting beyond what a monitor setup can address.

Check whether the computer is actually running

A black monitor can also mean the computer itself is off or not starting up. Listen for fan noise coming from the computer tower or feel for warm air coming out of the vents. If you do not hear or feel anything, the computer may not be powered on. Press the power button on the front of the computer and wait 30 seconds to see whether the monitor lights up.

If the computer is a laptop, it may be in sleep mode instead of fully off. Press any key or click the trackpad to wake it up. If the screen stays black after you wake the laptop, try plugging in the power adapter — a laptop with a very low battery may not display anything on the screen even though the computer is technically on.

Frequently Asked Questions

What if the monitor shows a picture during startup but goes black once Windows or Mac loads?

This usually means the graphics driver — the software that tells the computer how to use the video port — is not working correctly. Restart the computer and try pressing a key or moving the mouse to wake it from sleep mode. If that does not work, you may need to reinstall or update the graphics driver, which typically requires accessing the computer's settings or downloading software from the manufacturer's website.

Can a monitor go black if it overheats?

Yes. Monitors have a thermal protection feature that shuts them off if they get too hot. Make sure the monitor has space around it for air to flow, and check that the vents on the back are not blocked by dust or cables. If the monitor stays off after cooling down for an hour, try plugging it in again.

Does a black screen mean my monitor is broken?

Not necessarily. A black screen is usually caused by a loose cable or the computer using a different video port. Only if you have tried all the cable and port checks, and the monitor does not show a "no signal" message, should you assume the monitor itself is broken.

What if I see a cursor or hear sound but the screen is black?

This means the computer is running but the monitor is not displaying the picture correctly. Try restarting the computer, or if you are comfortable doing so, try updating the graphics driver. You can also try pressing Windows key + P (on Windows) or Command + F1 (on Mac) to cycle through display modes, which sometimes restores the picture.