Hi, @hartleek and welcome to the Canvas community!
First of all, I'm so sorry that this happened to you! I answered a similar question about this last night.
I do not believe there will be a way to retrieve this information. I highly recommend that you type up future discussion board responses in word and then copy/paste. That way if anything does happen, your original will be safe.
There is some good news moving forward -- the folks at Canvas just released a new feature that automatically saves text editor work up to an hour but your school would have needed to have this feature turned on and from the sound of it -- it might not have been turned on at your school. The good news is every school will get this update added by July 2020.
From My Discussion Board Response is Gone!
As for the keyboard key that is causing this, it is likely the F5 key. That one usually serves as a refresh key.
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