Here i am writing some solution of Warning : Cannot modify header information – WordPress headers already sent by may be help of you.
1. Clearing your browser cache and cookies may resolve this problem. Also, check your search.php and index.php template files for errors.
2. It is usually because there are spaces, new lines, or other stuff before an opening tag, typically in wp-config.php. This could be true about some other file too, so please check the error message, as it will list the specific file name where the error occurred.
3. I add ob_start(); to top of .php file and works – magic < ?php ob_start(); ?>