Github overwrote local file with version from cloud

I spent the day working on a file. When I went to push to origin, I got a message saying there was a conflict. The choice was to use master file or file. Thinking ‘file’ meant my local file, I choose that option and then push. For some reason, github desktop wiping out all of my work and wrote the original file to my local computer. How can I recover all my work? I didn’t find a backup in the recycle bin as github desktop sometimes does.