I deleted a repository or stripped commits, can you restore the data?
No. You are responsible for backing up your repository. Creating a regular backup can protect you repository from accidental, user-caused, data loss.
While Bitbucket takes backups regularly, these backups are only for site-wide disaster recovery purposes. Site-wide disasters are events that impact large numbers of users. If you accidentally destroy code or delete your entire repository, Bitbucket cannot recover your loss for you.