First, use FTP to replace the functions.php file with a good copy and without the IP change function. See Filezilla and FTP Clients « WordPress Codex.
Second, add these two lines to your wp-config.php a few lines of white space below the opening <?php
to change back to the IP:
define('WP_HOME','http://your-ip-address');
define('WP_SITEURL','http://your-ip-address');
After your site is back up with the IP, use interconnectit.com WordPress Serialized PHP Search Replace Tool to do a correct find/replace in the whole database, after you do a database backup from Bluehost's Cpanel. See http://codex.wordpress.org/Backing_Up_Your_Database
If the site doesn't come back up with the lines above in wp-config.php, go ahead and use the Interconnect script to change them in the whole database, but backup your database first.