Can’t login to admin

I just upgraded to 2.0.5 (the upgrade to 2.0.6 failed miserably) and imported the database backup after which I am unable to login to the admin interface. I use the username and password I set when creating the WP instance but it does not work. When I request an email with the login information, WP tells me that the username I use does not exist. Any idea what I need to do?

Thanks in advance!