The input speakers aren’t working

If the internal speakers on your Mac aren't working

If you don'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.

1. From the Apple menu , choose System Settings (or System Preferences).
2. Click Sound.
3. Click the Output tab, then select the built-in speakers. If you don’t see built-in speakers as an option in the Output window, contact Apple Support.
4. If the Output volume slider is set low, move the slider to the right and test again.
5. If the Mute checkbox is selected, deselect it and test again.
6. If you still don’t hear any sound, contact Apple Support.

While you are at it try the SMC Reset too

Reset the SMC of your Mac - Apple Support (CA)

Also >>

1 - Restart in Safe Mode. This will perform a Disk Repair, clear cache files and only load Apple Software, extensions and fonts. The boot up will be slow and can take some time - Normal.

2 - Safe Mode will also eliminate Third Party Software, extensions and drivers from loading. It will only load the Minimum amount of Core Apple Processes to allow the the computer to function at a reduced Level of Performance 

3 - Does the issue present in this mode ?

4 - Sometimes a Safe Boot followed by a Normal Boot will just put things right.