No video sound

I recently found an old (2010) SD card and slide it into my Mac to find photos and videos of my last day of high school. I click on the videos and they play but there is no sound! Naturally I would like to be able to hear what was going on that day so I can save it to my hard drive. Thinking the problem was with my Mac, I slid the SD card into a digital camera and the photos show but the all the videos say that they are an unrecognized format. Anyway to correct this and recover the sound?? Any help would be greatly appreciated and thanks in advance!

Hi, hope my answer is still helpful, you can download a free grabber.  First you should backup your sd card  into a DVD folder, and then use the grabber to convert it into other formats, mp4 is a popular format, many equipment will support this format, so you can convert DVD folder to mp4, the specific operation you can refer to this article :smiley: