Start with the simplest checks first
A monitor that won't turn on usually has power reaching it but the display is off, or power isn't reaching it at all. Before you troubleshoot anything complex, check three things in this order: whether the power cable is plugged in at both ends, whether the monitor's power button is actually on, and whether the cable running from your computer to the monitor is connected.
The power cable has two ends — one plugs into the wall outlet or power strip, and one plugs into the back of the monitor. Both connections can work loose from vibration or being bumped. Trace the cable from the wall all the way to the monitor and make sure both ends are seated firmly. If the outlet itself is the problem, plug a lamp or phone charger into the same outlet to confirm power is there.
The monitor's power button is usually on the front, bottom edge, or sometimes on the side. Press it and hold for two seconds. Some monitors have a very subtle light that shows power is on — look for a small LED, usually white or blue, somewhere on the front or bottom bezel. If you see no light at all after pressing the button, the monitor is not receiving power.
Key Takeaways
- Check that the power cable is plugged in at both the wall and the monitor, and that the monitor's power button is pressed on.
- Make sure the cable connecting your computer to the monitor (HDMI, DisplayPort, or VGA) is plugged into both the monitor and the computer's graphics port.
- If the monitor has power but no picture, restart your computer completely — do not just wake it from sleep.
- Try a different power outlet, a different cable, or a different computer to narrow down whether the problem is the monitor itself or something connected to it.
- If the monitor shows a "no signal" message or blue screen, the monitor is working but not receiving video from your computer.
Confirm the video cable is connected to the right port
The cable that carries the picture from your computer to the monitor is separate from the power cable. This is usually HDMI, DisplayPort, or on older monitors, VGA (a blue connector with three rows of small holes). Trace this cable from the back of your monitor to the back of your computer tower or laptop dock.
On the monitor end, the cable should be plugged into a port labeled HDMI, DisplayPort, or VGA. On the computer end, it should be plugged into the graphics card or the back of the tower — not into a USB port or audio port by mistake. If you have multiple ports on your computer, try unplugging the cable and plugging it into a different video port, then restart the computer.
Laptops are trickier because the video port might be Thunderbolt, USB-C, or HDMI depending on the model. Check your laptop's manual or the manufacturer's website to confirm which port outputs video. If you are using a docking station, the cable should go from the dock to the monitor, not from the monitor directly to the laptop.
Restart your computer completely
If the monitor has power (you see the LED light) but shows a black screen or "no signal" message, your computer may be on but not sending video. Do not just press a key or move the mouse — do a full restart. Hold the power button on your computer tower or laptop for ten seconds until it shuts down completely, wait five seconds, then press the power button again to turn it back on.
While the computer is restarting, watch the monitor. You should see text or a logo appear on the screen within 10 to 15 seconds. If nothing appears, the computer is either not sending video or the monitor is not receiving it. Once the computer finishes starting up, you should see the login screen or desktop.
Test with a different cable or outlet
If the monitor still has no power light after you have confirmed the cable is plugged in, try plugging the power cable into a different outlet. Some outlets are controlled by a wall switch, or the outlet itself may be broken. Plug a lamp into the same outlet first to confirm power is there.
If a different outlet works, the original outlet is the problem — contact an electrician or stop using that outlet. If the monitor still has no power light even in a working outlet, try borrowing a power cable from another monitor or device that uses the same connector type. If a different cable works, your original cable is damaged and needs to be replaced.
For the video cable, unplug it from both ends and plug it back in firmly. If the monitor still shows "no signal," try a different video cable if you have one available. A damaged HDMI or DisplayPort cable is common and straightforward to replace — they cost between five and fifteen dollars.
Try the monitor on a different computer
If you have access to another computer, connect your monitor to it using the same cables. This tells you whether the problem is the monitor itself or your original computer. If the monitor works on the second computer, the issue is with your original computer's graphics card, drivers, or settings — not the monitor.
If the monitor still does not work on a second computer, the monitor itself is the problem. At this point, the monitor likely needs repair or replacement. If the monitor is under warranty, contact the manufacturer with the model number (usually on a sticker on the back) and describe what you have already tried.
Check for a brightness or contrast dial
Some monitors have a physical brightness dial or buttons on the front or side. If the monitor has power and is receiving video but the screen appears completely black, the brightness may be turned all the way down. Look for a dial, knob, or buttons labeled with a sun icon or the word "brightness." Turn the dial clockwise or press the up button repeatedly and watch the screen.
Older monitors especially may have a contrast knob as well. If brightness does not help, try adjusting contrast. These controls are usually on the bottom front edge or the right side of the monitor bezel.
Look for an input or source button
Monitors with multiple video inputs (HDMI, DisplayPort, and VGA on the same monitor) have an input or source button that lets you choose which port to display. If you have plugged the cable into one port but the monitor is set to display a different port, you will see a black screen or "no signal" message.
Look for a button on the front of the monitor labeled "Input," "Source," or with an icon that looks like overlapping rectangles. Press it and a menu should appear on the screen showing which inputs are available. Use the arrow buttons to select the input where you plugged in your cable, then press Enter or OK. If you are not sure which input you used, try each one until the picture appears.
Frequently Asked Questions
What does "no signal" mean on my monitor?
The monitor is powered on and working, but it is not receiving video from your computer. Check that the video cable is plugged in at both ends, restart your computer completely, and try a different video cable if you have one. If the message persists, the graphics card in your computer may need a driver update or repair.
Why does my monitor turn on for a second then go black?
This usually means the monitor is receiving power but losing the video signal. Unplug the video cable from both the monitor and computer, wait ten seconds, and plug it back in firmly. If it happens again, try a different video cable. If the problem continues, restart your computer in safe mode to rule out a software issue.
Can I fix a monitor that won't turn on myself?
You can test and troubleshoot using different cables and outlets, but if the monitor has no power light after trying a working outlet and a different power cable, the internal power supply is likely damaged. This requires opening the monitor, which is not safe to do yourself. Contact the manufacturer or a repair shop.
Is it cheaper to repair or replace a monitor that won't turn on?
Repair costs vary widely depending on the problem and the monitor's age. For monitors under three years old, repair may cost between fifty and one hundred fifty dollars. For older or budget monitors, replacement is often cheaper. Check the warranty first — many monitors have a one or two year warranty that covers power failures.
Why won't my monitor turn on even though my computer is on?
The monitor and computer are separate devices with separate power supplies. Check that the monitor's power cable is plugged in and the power button is on. Then check that the video cable connecting them is plugged in at both ends. If both are connected and the monitor still has no picture, restart your computer completely.