Fix Built-In Speaker is Not Working/No Sound on MacBook
Check the output source and other settings
Select the Output tab and click built-in speakers. If that's not available as an option, contact Apple Support. Check if the volume slider is low; if so, slide it to the right and recheck the sound. Make sure the Mute box under Output volume isn't selected.
for command - sudo killall coreaudiod
Reset the NVRAM. Depending on what kind of MacBook you have, it may use non-volatile RAM (NVRAM) to store specific settings. Like any other memory, it benefits from an occasional reset. What you'll reset depends on your processor: If you have an Intel Mac, reset the NVRAM by shutting down the computer and restarting it while holding Command + Option + P + R.