Black screen but the laptop is on

• Press Ctrl + Win + Shift + B. This restarts the graphics driver on Windows.
• Raise the brightness; it may be turned all the way down.
• Press Win + P and choose 'PC screen only'.
• Connect an external monitor or TV with HDMI. If the picture shows there, the laptop screen or its cable is faulty.
• Hold the power button for 10 seconds to shut down fully and start again.

If the external screen also stays black, the problem may be RAM or the motherboard. Do not open the laptop yourself.