Regaining access without the admin interface.
FOR WORDPRESS
WP-CLI creates a user, resets a password, or promotes an existing user to administrator in one command. This is the fastest route.
Without WP-CLI, update the user's password directly in the database using phpMyAdmin, applying the correct hashing function.
Or add code to functions.php that creates an administrator, then remove it immediately afterwards.
IF PLUGINS ARE THE CAUSE
Rename the plugins directory over SSH or in File Manager. All plugins deactivate, and the login usually returns.
IF THE THEME IS THE CAUSE
Rename the theme directory. WordPress falls back to a default theme.
IF IT IS A REDIRECT LOOP
Check the site URL settings. Define them explicitly in wp-config.php to override whatever is in the database.
FOR OTHER APPLICATIONS
Most provide a command-line user creation or password reset. Check the documentation before editing the database.
AFTERWARDS
Work out why you were locked out. A compromise, a plugin conflict, or a configuration error each need different follow-up.
