There should have been an autosave in such a situation, unless what you had lost was input between the last autosave interval and the outage. “all of the work” sounds like more than an autosave interval’s (every 60 secs IIRC) worth of work. It is possible to disable autosaves, but IMO there’s little reason to do so.
Anyway, if there is no autosave evident for the post, I’m sorry to say that the content is likely permanently lost. There is one “hail Mary” attempt for recovery you could try, but don’t get your hopes up. You can use the phpMyAdmin app to directly search for the lost content in raw DB data.
Identify the post’s ID. It’s visible in the editor screen’s URL. In the app (usually accessed through your hosting account) navigate to the wp_posts table. Click the Search tab. For the post_parent field, enter the post’s ID, then click the Go button. You’ll get a list of all revisions and any autosave that exist for the post. You can open any record in the list for editing so you can see the actual post content. I recommend not actually editing anything here, look only.
If you do manage to find what you’re looking for, you can copy it from the edit screen back WP, but because it’s raw data, you’ll want to paste it into the post using the code view.
The phpMyAdmin edit screen has an annoying quirk. If you use your browser’s back button to try to return to the search results, it will not work, you’ll have to redo the search. Instead, at the bottom of the edit screen, use the Go button to save and go back to the previous page. It’s OK to re-save if you haven’t changed anything. Or pick the Show insert query option instead of Save. Ignore the query, you’ll be able to see the search results as well.
Good luck in your search.