Troubleshooting Steps:

1. Check if the laptop is plugged in, and that the charging LED light is lit
2. Check if the monitor cable is secure and tightly connected
3. Check if the laptop is in sleep/hibernation mode
4. Check if you have disabled the laptop display, and switch it back on
5. Check if the maximum brightness of the display is correctly adjusted
6. Check if the display brightness is too low, and adjust the brightness
7. Restart the laptop and open the lid to see if the display turns on