Press the button on the projector or the remote control to turn up the volume.
Make sure the A/V Mute feature is not enabled. (The A/V Mute button may have been pressed.)
Make sure the A/V mute slide (lens cover) is open.
If you’re using a VCR or other video source, make sure its volume is not turned all the way down or muted. Also, make sure the cables are connected correctly. See Playing Sound Through the Projector.
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’s headphone jack or audio out jack.
Make sure the Windows volume controls on your computer are not turned all the way down or set to Mute. You may be able to check this by clicking the volume control in your Windows Taskbar (lower right corner of the screen).
Make sure the Mac volume controls are not turned all the way down. You may be able to adjust the volume from your menu bar (top right corner of the screen) or with the volume control function keys.