I have a MacBook Pro and yesterday the sound just stopped working. It was funny cause I turned it off and tried and cool it down because I thought that it became too hot. After that it worked, but a few minutes later it just stopped working again.
Now there is no startup sound, there is no input and output device in System Preferences, and no, there isn't any red light. I also tried resetting PRAM and NVRAM with command-option-R-P.
I don't know what to do.