How can I get my audio input and output devices back? I have no sound and cannot see any of the devices in Audio MIDI Setup..??

Question

Hi, I tried to set up a new output audio device on my mac that would have multiple outputs (iBox Twist speaker and my internal speaker) but when I went to click onto one of the iBox Twist (there were 2 options available: iBox Twist and iBox Twist Stereo), Audio MIDI Setup crashed and when I finally got that back open, I found that there were no audio input or output devices to be found. My sound is working, as when I turn on my iMac, the starting sound still plays, however the volume control in the menu bar is no longer a black colour, but grey and when I try to change the sound on my keyboard it does not change. This already happened to me once, and after 3 hours I managed to fix it very simply (switching off Mac, unplugging power cord, leaving for 15 seconds, plug power cord back in and switch Mac back on, holding Alt, Cmd, P and R keys until you hear the Starting Up sound twice) however this same technique that fixed it once before is not working this time and I am still stuck without sound. I have tried Repair Permissions, rebooting in Safe Mode, Hardware Test and checking for Software Updates. Has anyone else had this problem and managed to fix it?
Thanks in advance for any help anyone can give me!

Answer 1

In case anyone has had the same problem as me, I have just managed to fix this by doing the following:
Switch off Mac
Switch back on in Safe Mode (Hit power button, then hold Shift key until a loading bar appears at the bottom of the screen).
Switch off Mac again
Remove power cord and wait 15 seconds
Plug power cord back in and hold down the keys alt, cmd, p, r all at the same time until you hear Starting chime for a second time and hopefully your audio will back.