MacBook Air
My MacBook Airs sound is not working and it just came in the mail today. It worked as soon as I received it and then I shut it off for about 3 hours and now the sound is not working.
MacBook Air 13″, macOS 10.15
When you says the sound's not working, do you mean the internal speakers? Try following these trouble-shooting guidelines from Apple first, including starting with making sure you are running the most up to date version of Mac OS. Have you connected any Bluetooth devices? Wired headphones?