WordPress has locked me out. Can’t use wp-admin.

I am in urgent need of instructions on how to proceed now that a fatal error has rendered wp-admin inaccessible. I can no longer log in to my wordpress due to a fatal error that appeared out of the blue (i.e. nothing was done to the install (2.8.2) between yesterday, when it worked just fine, and today, when I can’t access control panel at all.

(tells me Fatal error: Call to undefined function delete_transient() in /var/www/monetate/blog/wp-admin/upgrade.php on line 23)

Is it possible to recover without using the admin panel? I have read the manual upgrade insstructions [which look like a morning’s work to me] and when you get to step 9 it says run the WordPress upgrade program from wp-admin but I can’t run wp-admin.

Thanks…Stephen