Macbook Air No audio.

Hello, I own a Macbook air bought late 2012, and about 2 months ago the sound stopped working. Although i some-how fixed it, and the sound started to work. But in the present, my Mac doesnt make any noises. I read many discussions, and no my headphone jack isn't stuck. I restarted my laptop many times, and couldn't hear the start up chimes, except for this one time. Once i heard it, i thought i had fixed my mac, but i still couldn't adjust the volume, instead there was a sign which crossed it out. I started restarting my laptop a couple more times, and now im getting frustrated. When i go into Preferences - Sound it says there are no devices found in the input and output section. I ran Apple diagnostics, and it say's there are no hardware issues. Please help!!! 😟😟