My website is throwing “PHP Fatal error: Call to undefined method CI_Lang::lang()”-Collection of common programming errors

See the thread attached to the library: http://codeigniter.com/forums/viewthread/179036/ [edit: Link broken; cannot find alternative. For some reason Ellis Labs decided to move the forum and break everything.] In the first post is attached a modified library that claims to alleviate the buggyness of the original.

There is also a post on the first page there referencing an error similar to yours:

After copying the files as described in the article I get the following error: Fatal error: Call to undefined method CI_Lang::CI_Lang() in /www/websites/audio-machinery/application/core/MY_Lang.php on line 32

Though he seems to be calling CI_Lang, not Lang. His solution appears to have been to use the code attached to the forum thread.

Also, cpanel is a control panel for hosting, not a hosting provider. But your hosting provider may be causing issues (e.g. if using older versions of PHP which do not work with newer version of CI. Often hosting providers will give you the ability to choose which version of PHP you are using–usually found in cPanel).