Hi there, @BellaLevine ...
I am sorry to read that you lost your text that you had been typing. I totally agree with @chriscas on this one. I wanted to provide you with a Guide that also describes how the auto-save feature should work within the RCE (Rich Content Editor).
How do I add and modify text in the Rich Content Editor as a student?
Scroll about three-quarters of the way down the page, and you'll find a section on "View Auto-Saved Content" and "Load Auto-Saved Content".
I would also add that if you plan on typing a lot of text as part of a discussion topic reply, you might want to consider typing that "offline" using something like Microsoft Word and then pasting that text into your response in your course. That way, you will still have a copy of it if the text gets lost...like you described.
Hopefully this extra bit of info will also be of help to you. Good luck!