Sound not working

I have the same issue. Although I'm starting to think it's a hardware problem.

I have no sound from either my internal speaker or from headphones, opening garage band brings up an error code "Core Audio: Selected Driver not found. (-10202)"

Pressing the volume buttons on the keyboard flashes up the level indicator on the screen but it does not change, and also a little "O" with a line through it appears underneath. The Sound Preference panel says "No Output Devices Found", and the volume slider is grayed out, set to max, with a grayed Mute box ticked.

Is yours the same?

I'll do some more digging and let you know what I find?

I too have lost my sound
Any help ?

I have the same problem. However, for several days, sound would come back with a reboot, which leads me to believe it is software, not hardware. But now, even rebooting doesn't work. I don't even get the boot 'chord'.

Same here, I can hear a very very little sound very I put the volume into the highest. On the sound output preferences, it just shows the selected device has no output controls.

Same problem as in Boot camp too, so I think it must be driver related.

I too have lost my sound..... ggggrrrrrrr... 😟

i have no sound WHY?? can someone help im starting to hate apple

Lack of sound on is usually a hardware failure. On some MacBook Airs, the cable connecting the speaker to the system goes south.

I would take the machine to an Apple Store or an Apple-Authorized Service Provider and have it looked at.

I'm having a similar issue with my new MacBook Air. My speakers work to play movies, etc, but none of my alert sounds or iChat sounds work. I rebooted and it worked fine, but then they stopped working the first time I woke the computer up after the reboot. Am I correct in guessing it's a software issue because the speakers do work with other applications?

Your problem is not the same as mine.
I have nothing, can't use headphones nothing.
Itunes doesn't show song is playing
MySpace jukebox doesn't show song is playing etc
No sound what so ever.

I do have sound on a lucky day but they are now further apart

I found this answer through Apple's online support. Did it and my sound returned!
Online support indicates that the PRAM and NVRAM need to occasionally be reset.

Resetting your Mac's PRAM and NVRAM
2010-06-25 21:25:31 GMT
Products Affected
Portable Computers, Desktop Computers
Introduction

This document explains how to reset the parameter random access memory (PRAM) and nonvolatile RAM (NVRAM) on Macintosh computers.
How To

Important: If your computer does not retain parameter RAM (PRAM) settings when it is turned off, this generally indicates that the battery needs to be changed. Refer to Macintosh Family: Batteries and Part Numbers.
Resetting PRAM and NVRAM

1. Shut down the computer.
2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3. Turn on the computer.
4. Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
6. Release the keys.