Can’t login to my Dashboard – Please Help

When I go to my log-in page this message is across the top:

Warning: Cannot modify header information – headers already sent by (output started at /home2/stevecor/public_html/wordpress/wp-content/themes/nebula-10/functions.php:7) in /home2/stevecor/public_html/wordpress/wp-login.php on line 255
Warning: Cannot modify header information – headers already sent by (output started at /home2/stevecor/public_html/wordpress/wp-content/themes/nebula-10/functions.php:7) in /home2/stevecor/public_html/wordpress/wp-login.php on line 267

If I try to log in I get this message, but no dashboard:

Warning: Cannot modify header information – headers already sent by (output started at /home2/stevecor/public_html/wordpress/wp-content/themes/nebula-10/functions.php:7) in /home2/stevecor/public_html/wordpress/wp-login.php on line 255

Warning: Cannot modify header information – headers already sent by (output started at /home2/stevecor/public_html/wordpress/wp-content/themes/nebula-10/functions.php:7) in /home2/stevecor/public_html/wordpress/wp-login.php on line 267

Warning: Cannot modify header information – headers already sent by (output started at /home2/stevecor/public_html/wordpress/wp-content/themes/nebula-10/functions.php:7) in /home2/stevecor/public_html/wordpress/wp-includes/pluggable.php on line 658

Warning: Cannot modify header information – headers already sent by (output started at /home2/stevecor/public_html/wordpress/wp-content/themes/nebula-10/functions.php:7) in /home2/stevecor/public_html/wordpress/wp-includes/pluggable.php on line 659

Warning: Cannot modify header information – headers already sent by (output started at /home2/stevecor/public_html/wordpress/wp-content/themes/nebula-10/functions.php:7) in /home2/stevecor/public_html/wordpress/wp-includes/pluggable.php on line 660

Warning: Cannot modify header information – headers already sent by (output started at /home2/stevecor/public_html/wordpress/wp-content/themes/nebula-10/functions.php:7) in /home2/stevecor/public_html/wordpress/wp-includes/pluggable.php on line 850

All of this started Friday Night when I tried to add some code as described here:

https://weblogtoolscollection.com/archives/2009/04/10/how-to-highlight-search-terms-with-jquery/

Using my webhost login, I changed the files back to the original code, but haven’t been able to get into my dashboard since.

Any help would be greatly appreciated. I have written a few things here for my children that I’d really hate to lose.