I\'ve a repo on https://bitbucket.org/
Few days ago by a mistake big number of image files were pushed in the repo. then files were deleted via another push. after that
If you are the only one using this repo, you can follow the git filter-branch option described in "How to purge a huge file from commits history in Git?"
The simpler option is cloning the repo to an old commit, and force push it, as described in "git-filter-branch to delete large file".
Either one would force any collaborator to reset his/her own local repo to the new state you are publishing. Again, if you are the only collaborator, it isn't an issue.