I had a lot of local changes.
I just accidentally did
git merge another_branch
git reset --hard HEAD^
on a lot of work. :( with the intention I didn't want the merged changes in here.
How do I recover the original state?
No, the local changes were never committed/stashed.
No way?
If the changes had never been committed/stashed/staged, then you're out of luck. If they have, then you should be able to git your changes back by looking for them in git reflog.
Although the uncommitted modifications to tracked files will have been lost, I think any untracked files will still be around unless you subsequently deleted them. But you probably already knew this.