I have Drupal 6 site. In deleting spammers I accidently knocked myself out. Can I reclaim admin on my own site? Help.
If u are able to create account,create it and in the database for the 'users' table update '1' to the 'uid' field for the account you created and if you are unable to create a account then create a account manually in the database
INSERT INTO users (uid, name, pass) VALUES ('1', 'yourname',> md5('yourpassword'));
Default method should be to backup entire page before mass operations, and then restore it in case of failure. If you cannot do it on your own, your hosting company probably have nightly backups they can restore for you if you ask them.
If that's not the case, but you can access SQL console or SQL web admin tool, see this answer.
If you can't access SQL console directly, but have file access, you can put SQL code in settings.php wrapped in db_query(), but be extremely careful, as it gets executed on almost every page hit.