Question: The volume on my macbook pro has suddenly become greyed out. I haven't installed any updates or made any modifications to the computer, it just suddenly became greyed out after waking the macbook up from sleeping.

I've tried resetting the PRAM, but I don't hear any chime at all when I start up my computer, no matter how long I wait/how many times the computer re-restarts itself.

There also seem to be no internal speakers detected when I go into system preferences. For both input and output the computer detects 0 devices.

Thanks so much in advance for any help!!

Answer: 
Try switching back to your internal speakers with [alt]-clicking on the speaker icon in menubar. Many interfaces don't support volume adjustment and thus the control becomes greyed out.

![enter image description here](https://i.stack.imgur.com/ytgxf.png)
Try picking up some [compressed air](http://www.mcmelectronics.com/product/CHEMTRONICS-ES1027-/20-4468) and using it to blow out any dust or debris that might be in the headphone jack. Make sure to first expel any liquid build (white frost-like substance) before you spray in the headphone jack.  

You can also try fishing around in there (gently) with a ridiculously small [flathead screwdriver](http://www.mcmelectronics.com/product/26101).  

One question for you, is there a red light coming out of the headphone jack? That's usually a bad sign that the audio jack thinks there's an optical audio device plugged in (permanently.) If you're MacBook is under warranty the Genius Bar will replace the Main Logic Board for free (or about $300 if it is Out of Warranty.)  

Otherwise, the simple and inexpensive [Griffin iMic](http://store.griffintechnology.com/catalog/product/view/id/623/s/imic/) will provide USB audio input & output.