Hey there, ChristopherAndrade,
Thanks so much for using Apple Support Communities.
If your video doesn't have audio, the first thing we would check is if you can hear audio from other apps such as the Music app or other videos in the Photos app that have an audio track. If you're able to hear audio in general, and the issue is isolated to just that one video, then it is unlikely you would be able to recover the audio since it may not have been recorded to begin with. However, if you are experiencing audio problems in general on that iPhone, then this article has some additional troubleshooting steps you can take: If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker - Apple Support
If you are concerned with your devices ability to record audio for future videos, then we would recommend checking out the troubleshooting steps you can take in this article: If the microphones on your iPhone aren't working - Apple Support.
We hope that this information is helpful.
Have a great day!