Well, if you did commit it, but just hadn't pushed it yet, and then somehow lost that commit, then git reflog would be the tool for it.
Without a commit, sometimes you may have already staged some changes for an upcoming commit and can roll back to that.

But if neither of those are the case, then I can't really imagine how Git should help you there. You haven't told Git about those changes yet, so it's out of scope.
At that point, you better hope your editor's undo history goes back far enough...