Adding Twitter plugin disables blog

So I’m messing with a Twitter plugin and suddenly everything terminates. When I go to my blog, or even try to log into the admin stuff, I get this message:

Fatal error: Call to a member function get_feed_permastruct() on a non-object in /nfs/c05/h04/mnt/78333/domains/martynchamberlin.com/html/blog/wp-includes/link-template.php on line 365

So everything’s inaccessible – blog, admin page, everything. By the way, line 365 of course reads

$permalink = $wp_rewrite->get_feed_permastruct();

I tried downloading WP again from www.remarpro.com and uploading it to see if things would fix themselves, and it didn’t. I’m guessing I’ve messed up the WP database, a thing I can’t fix. Is there any solution? I’ve panicked.