[SOLVED]

• Log into phpMyAdmin and navigate to the jos_plugins table.
• Look for the “User — Joomla!“.
• Ensure that it is published as mine was not (set published to 1 just in case).
• [Look for] in row “Authentication — Joomla” and “System – Core Design Login Confirmation plugin“
• Ensure that it is published as mine was not (set published to 1 just in case).

Reference – //www.pwrusr.com/web/cannot-login-to-joomla-backend-as-admin