Upgrade to 2.8 Disables Admin with ComicPress

I did a silly thing. After months of not upgrading anything, I pressed the automatic upgrade button in the back end and just knocked the admin clean out. The front of the site looks fine (https://www.afflicted.me.uk) but try accessing the admin (https://www.afflicted.me.uk/wordpress/wp-admin/)and I get this error:

Fatal error: Call to undefined function: cpm_wpmu_modify_path() in /home/sites/afflicted.me.uk/public_html/wordpress/wp-content/plugins/comicpress-manager/comicpress_manager_library.php on line 90

How can I change the theme back to default from within the database to get into the back end.

And no. I did not make a back up (as he kicks himself again and again and again).

Thanks!