I have an Aspire 5750Z laptop. My audio randomly stopped working. It was working the night before no problem. I hadn't done any updates to my laptop. My dolby disappeared.I have tried the acer recovery no luck and I even uninstalled the Realtek driver and downloaded the audio driver from Acer and reinstalled it. Now it shows the realtek and Dolby there and working and up to date but I still have no audio and I have a red X on the volume icon reading that no audio output device installed. My laptop is 3 years old and I'm running windows 7. I have a flag saying I can upgrade to windows 10 but haven't. My research has shown other people having this issue when they upgraded to windows 8 and 10 but I have not updated my OS. Can someone please help me?