1. Ensure the HDMI cable is connected to the device and the HDMI port.
2. Check that the HDMI port is enabled in your computer's BIOS settings.
3. Switch the input channel on your screen or device to the HDMI port the cable is connected to.
4. Restart your computer and check that the latest driver is installed.
5. Check that spelling and capitalization of the device in the device manager is correct.
6. Check whether other devices connected through the same HDMI port are working correctly.
7. Try reversing the ports, meaning plugging the HDMI cable into the other port.
8. If all above methods fail, replace the cable.