Needed to reinstall and lost blog

I had a problem yesterday when my blog was deleted from the server. My local files were ok. I tried to reinstall WP and upgrade to 2.6.5 at the same time. I copied the SQL info exactly as it had been on the previous version, and tried to install only to get an error to say that it was already installed. I just get a blank screen when I put in my URL.

Is there a way to reinstall WP and not lose the previous posts?