So, what happened?!
We've all learned this lesson the hard way. Save your documents after every major change or long work session. In Word and most apps, e.g., get into the habit of pressing command-S after every change that you wouldn't want to lose. When writing and emailing, I do that after every new paragraph I've written.
Also, save everything you're working on *before* closing a laptop.
You never know when disaster will strike.
One other note. Typically the brain remembers the last bunch of actions, even the gist of what was, say, written, or which formulas were changed, and so, even if you have to redo a bit of work, it's really not that hard!
Hope it worked out for you…