Why did my iMessages and texts just randomly disappear?

I was in the middle of texting on my iPhone 7, iOS 10 and realized all previous messages to that person had disappeared. When I went back and clicked on another set of messages, all messages except the most recent one had been deleted, but not by me. I tried closing the app and then went back and every single one was gone. Can anyone tell me why and how to fix this problem and receive all my messages back.