How to rollback git push --mirror

I copied one repository to another repository.
git clone --bare https://github.com/exampleuser/old-repository.git
cd old-repository.git
git push --mirror https://github.com/exampleuser/new-repository.git
accidentally deleted all branches.
tell me please how I can roll back the last git push --mirror repo command or restore everything?

It depends where and how you deleted them — on GitHub, via the WebUI? then look for the UNDO button.

Locally? how? which commands?

If you only deleted the branches in one end point (local vs GitHub) it should be easy to recover them, by either pulling and pushing them.

In any case, for local deletions, you can use the Git Reflog! Since this is a wide and delicate topic, read carefully the docs and some tutorials, before doing something that could make your deletions permanent (and unrollable):

https://git-scm.com/docs/git-reflog