Problem With Website

I was doing great creating my website and I was almost done and I decided to change the theme and as soon as I actived the featured theme my website has been showing this error message. I tried logging in to the admin page to fix it but it shows the same error message!

Fatal error: Call to undefined function wp_get_theme() in /home/tommy/public_html/wp-content/themes/news/library/functions/utility.php on line 119

Here is my website https://minecraftmachinima.net/

PLEASE FIX THIS NOW!!!!!!!!!!!!!!!!