I have been getting unwanted new user registrations. When I try to login to the admin panel I get this error, which has never occurred before saying: ERROR: Cookies are blocked or not supported by your browser. You must enable cookies to use WordPress.
Warning: Cannot modify header information - headers already sent by (output started at /home/content/85/9088985/html/wp-includes/general-template.php:2460) in /home/content/85/9088985/html/wp-login.php on line 415
It seems someone installed a plugin that has shut down my access. Any advice?