Press the button on the projector or the Vol+ button on the remote control to turn up the volume.
If you've turned off the picture and sound, press the A/V Mute button on the remote control to turn them on again or open the A/V Mute slide.
If you're using a DVD player or other video source, or external speakers, make sure their volume is not turned all the way down or muted. Also, make sure the cables are connected correctly. See Setting Up the Projector.
Make sure the audio cable is connected to the correct audio port. See the following for details:
If your presentation includes computer audio, make sure the volume control on your computer is not turned all the way down or muted. Make sure the audio cable is securely connected to both the projector and your computer. See Playing Sound Through the Projector.
The wrong source may be selected. Press the Source Search button on the projector or the remote control.