"I lost a commit!"

Spoiler: you almost certainly didn't. Git rarely throws anything away within ~30 days.

First, check `reflog`

git reflog

You'll see every move HEAD has made. Find the SHA you want.

If the commit was on a branch you reset:

git checkout <sha>            # look around
git switch -c rescued         # save it on a new branch

If you accidentally git reset --hard:

git reset --hard <reflog-sha>

Before destructive commands (reset --hard, rebase), make a backup branch:
```
git branch backup-$(date +%s)
```
Never --force-push to main.
Commit early, commit often.