Cannot access WP blog admin..dashboard etc. after automatic update yesterday 6/28/12

I have updated using the automatic method before without problems. Yesterday I used the automatic update again but now I cannot access our band blog. I receive the following error code when trying to go to dashboard.
Fatal error: Call to undefined function wp_is_mobile() in /home/content/10/7985910/html/wp-admin/index.php on line 22

I have looked on the net and see many instances of problems like mine but no resoultion of problem. I am unable to access any files so cannot make changes.

Any thoughts much appreciated.

Cheers, Dave