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)
I have had the same problem twice. And what I did was (for the first time[i am listing two so there are more possibilities]) 
1st. restart my laptop. I know that it sounds cliche. But it works most of the time. 
2nd. If all else fails. Try playing with the volume buttons on the keyboard. And this one sounds silly but it helps. Try the second one and then restart your laptop. That is what I did.