Please follow below instruction to do troubleshooting.
1. Verify that the audio cable is connected to the AUDIO OUT or LINE OUT output on the Sound Card and plugged into the AUDIO IN or LINE IN of the Monitor.
2. Make sure there are no cables connected to the Headphone Jack (located next to the AUDIO IN port) on the monitor.
If there is, please disconnect that cable and try the speakers again. Connecting a cable to the Headphone Jack disables the speakers.
If there is no cable connected into the Headphone Jack, test a pair of headphones into that jack to see if you can hear sound out of the headphones.
If you are able to hear sound out of the headphones, disconnect the headphones and try the speakers again.
3. Verify that the Mute on the monitor is not on or the Volume is not turned down.
4. Verify that the Mute on the computer is not on or the Volume is not turned down.
5. If there is still no audio from the monitor's speakers, connect the Audio cable to another audio source like a portable CD player or tape player headphone output.
If audio can be heard through the monitor's speakers, then there may be an issue with the computers sound card.
6. Connect another set of computer speakers (if available) or headphones to the AUDIO OUT or LINE OUT output on the Sound Card.
Right click on the speaker in the systray and check to see if the correct playback device is available and selected.
If NO audio can be heard then there is an issue with the sound card or sound card drivers.
Verify with the computer's manufacturer for additional assistance.