File backup is stored in the folder, but can you tell me how to recover it?

My computer shut down unexpectedly for a while as I left. Starting again d5r has opened a previous file without working all morning. I went to retrieve the historical files but saving the most recent copy gives me an error and I can’t update it. Yes, a .backup is stored in the folder, but can you tell me how to recover it? Thank you so much.

Hello, please watch this video, normally we can click the “View version history” button.

If that button is greyed out, please let me know, I think some errors may happen, but we have the solution.
Please backup your files first and do not open it multiple times.