Fix 1: Check audio output device
Apple menu → System Settings → Sound → Output. Make sure 'MacBook Speakers' or 'Internal Speakers' is selected. Often Mac auto-switches to Bluetooth speaker / AirPods / external monitor and stays there.
Common scenario: you used AirPods earlier, walked away with them, Mac still routes audio to disconnected AirPods. Switch back to internal speakers.
Fix 2: Check volume + mute state
Press volume-up key. Some keyboards have it as F12. Watch for the volume indicator on screen. Confirm volume isn't at zero.
Check menu bar for sound icon — if there's a slash through it, sound is muted.
Apps can have their own mute: check the volume control in Spotify, YouTube, Zoom, etc.
Fix 3: Reset Core Audio
Open Terminal. Type: sudo killall coreaudiod — press Enter, type password. Audio service restarts. Test sound again.
Solves ~25% of 'no sound' bugs without restart.
Fix 4: Check for crackling/distortion
If sound works but distorts: open Audio MIDI Setup (Applications → Utilities). Set output format to 44.1 kHz, 16-bit Integer. Some audio drivers force 96 kHz which causes crackles on internal speakers.
Crackling on one channel only often = software, not hardware. Stereo test: play test tone (System Settings → Sound → Output → Test).
Fix 5: SMC + NVRAM reset (Intel Macs only)
NVRAM stores volume preferences. NVRAM reset: power off, power on while holding Cmd+Opt+P+R until you hear startup sound twice. Mac forgets old volume settings.
SMC reset: power off, hold Shift+Control+Option + Power for 10 seconds. Re-power. Often fixes 'sound works sometimes' bugs.
Fix 6: Update macOS
System Settings → General → Software Update. Audio-driver bugs are common in early major-version macOS releases. Latest patch often resolves.
When it's hardware
Diagnostic check: External headphones via 3.5mm jack play sound, but internal speakers don't = speaker hardware fail. External Bluetooth works but jack and internal both fail = audio chip on logic board.
Speaker replacement cost: PKR 12,000–25,000 fitted depending on model. Logic board audio chip rework: PKR 25,000–45,000.
Liquid damage in the speaker grille area is a frequent cause — once water reaches the speaker membrane, it warps and distorts permanently. Common in monsoon season.