There are a few things you can do to reverse sound on TikTok videos. First, make sure that your phone is set to “voice memo” mode. This will allow you to record your voice and then play it back later. Second, use the “reverse sound” feature of your phone’s audio player. This will cause the audio in your videos to be played backwards. Finally, try using a software app like Audacity or VLC to fix any audio issues that may have occurred.