I have the original iPad and I recently downloaded the most recent software update and downloaded the latest version of iTunes. Prior to doing this, the videos on my iPad worked perfectly. After updating everything, certain videos do not produce sound. The videos I have purchased from iTunes still work without a problem, but the other videos that I ripped to MP4 files and uploaded to my iPad do not have any sound. I have tried everything, including restoring my iPad. I hope someone can help me!