what happens when I change the URL on my wordpress?

I accidentally changed the url and it completely wipedout, meaning it didn’t exist anymore — but my friend uploaded everything again.

However now it says "Fatal error: Class ‘SimplePie_Cache’ not found in /home/finch/public_html/wordpress/wp-includes/class-feed.php on line 6" for Development Blog & Plugins…..anything I have to worry about?