Fix a git mistake without losing work

Help me recover from a git mistake without losing any work, so that I can carry on from a clean state. I will run your commands myself in a terminal, one at a time, so they need to be exact.

What I was trying to do: {{intent}}
What I did, as best I remember: {{what_happened}}
Whether the commits were pushed, and who else works on the branch: {{shared_state}}

Output of git status, git log --oneline --graph --all -n 20 and git reflog -n 20:
"""
{{git_output}}
"""

Reply with:
1. What happened, in two or three sentences, based on the output above.
2. A safety step first: the command that creates a backup branch or tag of the current state, so nothing can be lost while we fix it.
3. The recovery steps, numbered, one command per step, each with what it does and what I should see afterwards.
4. How to check the result: the command that shows the branch is right, and what it should show.

Use the fewest commands that do the job, and explain each one in a plain sentence, because I need to understand what I am running. Make sure the backup step comes before anything that moves or deletes commits.

For example, the form of one step: "3. git cherry-pick a1b2c3d (copies your commit onto this branch; you should see 1 file changed)."

Avoid commands that rewrite shared history, such as git push --force or a rebase of a pushed branch, unless the branch is mine alone. If one is truly needed, say so plainly, use git push --force-with-lease instead, and tell me who to warn first. Do not suggest git reset --hard, git clean, or discarding changes to files until the backup step is done. Base every step on the output I pasted, not on what usually happens. If the output does not show the commits or changes I mention, say what is missing and ask me to run a specific command rather than guessing commit hashes. If a password, key or token was committed and pushed, tell me to revoke it first, because removing it from history does not make it safe again.