I have lost sound from my in built speakers after updating to Yosemite 10.10.5 how do I get my sound back?

Judy ...

Try this support article > Troubleshooting issues with no audio from built-in speakers on Macs

Go step by step and test.

1. System Preference > Sound > Output > Internal Speakers

Highlight Internal Speakers.

Make sure that Mute is not enabled.

2.Plug in and remove the headphone.

If you see red light in the headphone port, plug the headphone

in and out of the port 5 or 6 times to flip the microswitch inside.

Sound output may be stuck in the digital mode.

3. Reset SMC.

Choose the method for “On Mac notebooks with non-removable battery”.

https://support.apple.com/en-us/HT201295

4. Reset PRAM. http://support.apple.com/kb/PH18761

5. Applications > Utilities > Audio MIDI Setup

Audio Devices window

Side Bar

Click the Built-in Output.

Make sure that no box is checked under “Mute”.

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Try cleaning out the headphone jack and then insert a headphone several time. Sometimes the jack gets stuck.

Sound problems

In the Terminal, type that:

sudo killall coreaudiod

And in the sound preferences, make sure your internal speakers (and not HDMI or other device) is selected.

Other ressources:

http://www.iphonetopics.com/no-sound-after-upgrading-to-os-x-yosemite/

http://betanews.com/2014/08/26/how-to-fix-disabled-audio-in-os-x-10-10-yosemite- beta/

Re: OS X Yosemite - sound problems?