Laptop displays often may go haywire for one reason or another. Sometimes it's simply an AC adapter fix or a monitor brightness adjustment, while other times deeper problems may exist that require testing via the use of a VGA cable and an external monitor. These tests can be performed by a novice in computing with no heavy-duty tools or existing technical knowledge. When followed correctly, these guess-and-check procedures should uncover the source of your laptop display's affliction.
Check your AC adapter. Sometimes the problems that are the easiest to fix are the most common. Make sure the AC adapter is plugged into the back of your laptop securely and make sure the adapter is snugly placed into either your wall socket or your surge protector. Also, try plugging the adapter into a different wall outlet in case the socket it currently is in is no longer working.
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Adjust your monitor brightness settings. This is a simple test that may correct darkness on your laptop display, as sometimes these settings get inadvertently turned down all the way. The monitor brightness keys should be at the very top of your laptop keyboard just above the numeric keys. Use these keys to turn the brightness back up on your display.
Look at your laptop display closely to determine whether it seems dark but there is still a faint image on its screen. Locate the "LCD closed switch" on your laptop in this case. This switch will be found on the bottom of the laptop display, directly beside one of the hinges on your display (the left or right hinge, depending on your laptop model and its manufacturer). This switch normally operates by acting as a sensor that judges whether your laptop display is open or closed, and turns the display's back-light off appropriately. It may have gotten stuck in the "closed" position. Test this by tapping the switch several times with your finger in an effort to disengage it from the "closed" position. This may bring your display back to normal.
Test your laptop display to see if it is operating correctly at all or if it needs to be entirely replaced. Locate and utilize an external monitor and hook up your laptop. You can make this connection via the use of a standard VGA cable, which will run from the external display port on the back or side of your laptop and into the external monitor.
Turn on both the external monitor and your laptop. If the information from your laptop displays successfully on the external monitor, the issue lies directly with your laptop's screen and it will need to be replaced. However, if no image appears on your external monitor, your motherboard is at fault and your laptop should be completely replaced.