Fatal Error – Cannot get to my dashboard

I am a real amateur so if anyone can help, I would be most appreciative! I inherited a development site from a co-worker and I have been trying different themes. I uploaded Alexandria from Theme Alley and when I went to the Theme Editor, I got an error message. I tried it a few times and still got the same error. I then downloaded the Spine theme and when I went to activate it, I got this message:

Fatal error: Call to undefined function register_meta() in /homepages/6/d290726261/htdocs/iorio/wp-content/themes/spine/hybrid-core/functions/meta.php on line 46

I don’t know if the two errors are related. Now I cannot get to my dashboard or view the site. I am not sure what to do next.

Thank you.