Locked sound problem - Macbook Pro

Hello everyone,

I was recently giving a presentation that involved playing a short video. In order to play the video, I had to connect a HDMI cable to the projector, followed by a soundcable. When I plugged the sound cable into the port, the sound on my mac went off completely. When I try to adjust the volume settings, it shows a locked / forbidden icon.

I have also noticed that I am not capable of playing YouTube videos for longer than 3-6 seconds before they stop. In order to continue, I would have to click on where it stopped and the video would start playing again for 3-6 seconds before automatically stopping.

This problem has also affected by ability to play videos using the QuickTime Player, I get the following message:

"The document "DSC_0024.MOV" could not be opened. An unknown error occured (-101)"

I've done some research and looked for solutions, but nothing has worked as of yet.

1) You can try plugging in a different output device to 'trip the switch' and get the audio back on. I've tried this with my own speakers and apple headphones, unfortunately it did not work. I also have not seen a red light which I hear may indicate when there is a problem with the audio output.

2) I have tried running a hardware test and everything, including the sound card and logic board appears to be working perfectly fine.

3) Using the Disk Utility app, I have tried verifying and repairing disk permissions, still to no avail.

Does anyone have any suggestions I could try to solve this problem before resorting to pay money for a repair?

Please let me know, I would really appreciate it. 🙂