my MacBook Air, internal speaker no sound, if plugged in external speaker got sound, what happened?

JLQL Said:

"my MacBook Air, internal speaker no sound, if plugged in external speaker got sound, what happened?"

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Troubleshooting Internal Speakers:

A. Is there a Speaker Even Seen?:

To Find Out:

1. Go to: Apple menu
2. Select: About this Mac
3. Click: System Report... button
4. View: Hardware on left-column
5. Click: Audio
6. Verify: MacBook Pro Speakers is seen

B. Visit These Apple Support Links:

• If you can't Hear Sound from your Mac Speakers - Apple Support

• If the Internal Speakers on your Mac aren't Working - Apple Support

• Get Help if the Internal Speakers on your Mac don't Make Sound - Apple Support