Ganti Template jadi tidak bisa masuk ke meta login

Setelah ganti template, kok saya tidak bisa masuk ke admin melalui meta log in. Malah muncul tulisan :

Warning: Cannot modify header information – headers already sent by (output started at /home/bepotcom/public_html/wp-content/themes/lupercalia/functions.php:892) in /home/bepotcom/public_html/wp-content/plugins/quick-chat/quick-chat.php on line 262

Warning: Cannot modify header information – headers already sent by (output started at /home/bepotcom/public_html/wp-content/themes/lupercalia/functions.php:892) in /home/bepotcom/public_html/wp-login.php on line 418

Warning: Cannot modify header information – headers already sent by (output started at /home/bepotcom/public_html/wp-content/themes/lupercalia/functions.php:892) in /home/bepotcom/public_html/wp-login.php on line 431

ERROR: Cookies are blocked due to unexpected output. For help, please see this documentation or try the support forums.

Mohon bantuannya..