- Check to make sure that the laptop is compatible with the DisplayPort connection and the external monitor.
- Check that the cables are secure and that no errors occur in the connection.
- Restart the laptop.
- Unplug and replug both ends of the cable to ensure that it is properly connected.
- Check the DisplayPort settings in the graphics driver.
- If possible, try a different cable and/or shape of DisplayPort.
- If all else fails, try connecting the external monitor to the laptop via an HDMI input.