Can't login after wordpress automatic update 3.7.1

Hi there,

I tried to log into WordPress today and instead of the usual wp_admin page, I got ‘Welcome to the famous five minute WordPress installation process!’. It asks for a Site Title and email address, and has a spot for username which is pre-filled with ‘User(s) already exists’. When I fill in the other details, it refreshes the page and says ‘please provide a valid username’ but there is no way for me to fill in a username.

Any ideas? it seems the update was done automatically. The site is http://chocolatesapote.com if that helps.

Thanks in advance!