Firstly, check all cables, if you are using the HDMI cable you do not need the audio jack plugged in. Plugging in both will cause audio issues. If the cables are plugged in properly, check to see if the volume on the screen is turned up fully and not on mute. Also, make sure the speaker on the laptop/pc is not on mute and is also turned up fully.

It is also worth checking in control panel > sound and making sure the Touchscreen is selected for the audio output rather than the built-in audio for your laptop/computer.