how to fix this problem?

I run with WordPress 4.9.5 and php7.2 , I got the error msg when access catogory. How to fix?

Fatal error: Uncaught Error: Call to undefined function phpget_header() in /home/shhscom/public_html/test2/wp-content/themes/vella/category.php:1 Stack trace: #0 /home/shhscom/public_html/test2/wp-includes/template-loader.php(74): include() #1 /home/shhscom/public_html/test2/wp-blog-header.php(19): require_once(‘/home/shhscom/p…’) #2 /home/shhscom/public_html/test2/index.php(17): require(‘/home/shhscom/p…’) #3 {main} thrown in /home/shhscom/public_html/test2/wp-content/themes/vella/category.php on line 1

and i enable likeZilla plugin, I got

Deprecated: Function create_function() is deprecated in /home/shhscom/public_html/test2/wp-content/plugins/zilla-likes/zilla-likes.php on line 26

Please help to dix it.