Why Your Computer Screen Suddenly Went Black

Your monitor needs to communicate with the computer to produce an image on the screen. A black computer monitor indicates a breakdown in this communication, either with the computer or with the electricity necessary to make it all run. This could occur due to bad cables or an internal issue.

Loose or Failed Cables

Before assuming the worst, check the simplest fix first. Verify that all cables connecting the monitor to the computer are tight and secure, and that there are no visible marks indicating damage. Check the monitor's plug to make sure it's connected to a working wall outlet. Most monitors have a little LED near the power button that lights up when the monitor is on, so check to make sure it's getting power. Examine the video cables for any unusual crimping, as the wiring inside could short without noticeable outward damage. Swap both the video and power cables out to see if you get a picture with the new ones.

Bad Monitor or Video Card

Despite their sophistication, computer components don't last forever and are prone to unexpected failure. Your monitor may have suffered a short circuit, or simply died from an internal defect. The video card inside your computer tower heats up as it operates, which can cause damage if the temperature climbs too high. Connect a different monitor to your computer to check for a picture; if you get one, it might mean your previous monitor has gone belly up. If the new monitor still shows nothing but inky blackness, your computer's video card may have failed.

Overheating

All the components inside your computer generate heat as they operate, which can cause the internal temperature to climb to component-damaging levels if the computer's not properly ventilated. Small plastic fans are installed in all computers to help vent this heat before disaster strikes, but if they or the nearby case vents are caked with dust, lint and pet hair, that hot air inside your tower has nowhere to go. An overheating system typically displays warning signs such as frequent lock-ups, random shutdowns and loss of video. Keep your tower's vents open and clear, and periodically clean out the inside to let the air flow freely and keep things cool.

Total System Failure

Listen to your computer when your screen goes black. Is it dead silent or does it sound like it's still working properly? If the entire computer stops functioning when your monitor does, you could be looking at a total system failure. This can occur due to bad components, viruses or conflicting software; the exact problem can take a bit of trial and error to narrow down. Restart the machine and do some troubleshooting. Remove recently installed software or hardware, run an up-to-date virus scan and make sure the computer isn't overheating. Make notes of what programs you were running or any sounds the computer was making before all went black. Seek the help of a professional repair shop if the cause still eludes you and the blackouts keep happening.