Laptop computers are designed to automatically shut down their displays under certain circumstances. If a few keystrokes or a restart can't bring the screen back to life, however, it may be evidence of a more serious hardware issue.
Laptop computer
Inactivity
Most laptops are set to go into sleep or time-out mode and shut off their displays after a few minutes of inactivity in order to conserve power. If this is the case, pressing the space bar, power button or "ESC" key should bring the screen back to life.
Accidental Sleep or Time-Out Mode
You may have inadvertently hit a certain combination of keyboard strokes programmed to send the laptop into sleep or time-out mode. Hitting the space bar, power button, "ESC" or other random key should restore the display.
Low or Dead Battery
Some brands of notebook computer will automatically turn off the screen when their batteries are nearly drained, so they won't completely shut down and lose unsaved data. Plugging in the laptop's power supply should solve the problem; a restart may be required.
Lid-Close Switch Malfunction
The lid-close switch shuts the laptop's display off when the computer is closed and turns it back on when the computer is opened. The switch may be broken or stuck in the closed position.
Inverter Board or Backlight Malfunction
The inverter board in a laptop optimizes the power the computer supplies to the backlight, which illuminates its screen. Also known as a DC inverter or LCD inverter, the inverter board can fail and need replacement, or the backlight may be faulty.
Graphics Card Problems
Your laptop's graphics card translates the computer's actions into the visual representation seen on the screen. Although graphics cards rarely wear or burn out during regular use, dropping or jarring the computer may cause their connections to fail.
