Make sure the volume/ringer is turned all the way up.

Check that the sound icon on the video is turned on.
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Check that your device is able to play sound (try to play some YouTube video).

Safari browser now has a built-in feature that can prevent audio from automatically playing when visiting websites. This feature has the ability to block audio from online videos. This is easily solved by accessing the course through the Chrome browser.

Check that your device drivers are up to date

Try to play videos on other devices

Check if there is a hardware issue with the internal speaker or the headphones.
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