Unsecured Plug

• The cord may not be securely plugged into the video card on the PC. An unsecured plug can cause problems in the signal sent from the computer to the monitor.
  
  

Unsecured Video Card

• Sometimes when your computer is moved around, the video card in your computer can be jostled. If the card is not plugged in fully to your motherboard slot, you will see a black screen.
  
  

Brightness Settings

• A setting may be too low. Every monitor has a menu button, and within the onscreen menu is a "brightness" function. If your brightness setting is too low, the monitor will appear too dark.
  
  

Age

• The monitor may be old. If the monitor in question is a few years old and the other solutions don't work the picture tube may be going bad, in which case it is time to replace your monitor.
  
  

Disposal

• You cannot just put computer monitors in the garbage for collection. Call your local recycling center for information on how to dispose of a monitor.
  
  

Safety

• Make sure your computer is turned off before checking any peripherals for safety.