Over half of my most important chat just disappeared

I’m trying to worldbuild for a story, and I was using ChatGPT to do it. I wanted a refresher on a particular aspect, so I asked it to summarize it for me. It gave me some random made up stuff that wasn’t at all my original content. I went back through the conversation, and probably ~20 messages have just vanished, both mine and ChatGPT’s. The beginning and end of the conversation is all still there, it’s just the middle. Is there any way to get my information back? I need that for my story…