I have a MacBook Pro and I often encounter this issue: when I put the laptop to hibernate, and then when I reopen the lid, I can not hear any sound.
Later I found this post, which indicates that this is not a hardware issue, but a bug of MacOS of coreaudiod. There are several ways to solve it:
- open activity monitor, search audio and find coreaudiod, exit from it, and it will restart.
- another way is to enter
sudo killall coreaudiodin the terminal, or replug in the earphone. - restart is also an option.