Please try these troubleshooting steps that may help in solving the issue.
- Start by checking if your sound settings are all correct.
- Right click on the speaker icon and select Playback Devices.
- If you see your Acer Projector listed, right click on it and select Set Defaults.
- Click Apply and OK then test it again if it will give you sound.
If that doesn't work do a clean install the graphics card driver.
- Open Device Manager and uninstall the graphics driver.
- Check Programs and Features and uninstall anything related to your graphics card.
- Next is to download and install the latest driver from the manufacturers site.
- Reboot your laptop once the latest driver has been installed.
- After the reboot make sure to set the Acer Projector as the default Playback Device.