Can't access mywebsite.com/wp-admin

someon please go to http://atlantapropertyrestoration.com/wp-admin/

I get this error…why?

Warning: Cannot modify header information – headers already sent by (output started at /home/content/a/p/r/apr36670236/html/wp-content/themes/Chameleon/functions.php:1) in /home/content/a/p/r/apr36670236/html/wp-includes/pluggable.php on line 934