Just the other day, I upgraded my wordpress software and several plugins. The upgrade process broke the entire wordpress install and I wasn't able to login to the panel. I figured the only thing I could do was reinstall Wordpress, and then have it connect to the old, existing database.
This hasn't worked. I wiped clean the directory that my Wordpress blog was installed in, and told dreamhost to "custom" install a new wordpress installation and to use the old database. When I set up the new wordpress blog, however, it gives me a blank slate -- no old content from the database is there.