For reasons unknown the internal sound option has disappeared from my MBA. The little speaker icon on the menu bar is grayed out and nothing comes from the jack. Internal speakers don't even show up as an option under sound output. I do use an Airport Express for external speakers but it's been playing happily with the internal speakers for months. Searching various forums, I've learned of these fixes: 1) jiggle your headphone plug in and out while playing a song on iTunes 2) reset your PRAM... Tried both & neither worked. Help!