If the internal speakers on your Mac aren't working
If you can't hear sound from the built-in internal speakers on your Mac, make sure macOS is up to date and check your settings.
Check your sound settings
First, disconnect any cables from the USB, Thunderbolt or 3.5mm audio ports on your Mac.
From the Apple menu , choose System Settings (or System Preferences).
Click the Output tab, then select the built-in speakers. If you can't see built-in speakers as an option in the Output window, contact Apple Support.
If the Output volume slider is set to low, move the slider to the right and test again.
If the Mute box is ticked, untick it and test again.
If you still can't hear any sound, contact Apple Support.