You mean like you accidentally deleted all text versus just one sentence? It's probably too late now, but next time right click the text box and click "Undo".
There used to be this extension called Lazzerus (not sure if i spelled that right) that would keep track of content in a text box but I don't know if that's still a thing.
Thank you for the response, Jennifer. I got so flustered that I didn't even think to right click. I will also check out to see if that extension or one similar is available. Thanks again!