I upgraded to WP v3.5 on 12/11/12. Since I am using the Twenty Ten template on my web site, I thought I would install a second version of WP in a subdirectory of my domain root to upgrade and expand site content. When the new site was built out, I planned to migrate the new version to the root directory, replacing the old site.
I exported the web site database files (MySQL db: yogaman_wp1) to my home computer to save as a backup. I then added a subdirectory to my domain root called 'wp2012' and created a MySQL database called 'yogaman_wp2012'. This is intended as the home for the new 'Twenty Twelve' based web site.
I downloaded a copy of WP 3.5 to my computer, then uploaded the software to my web host via FTP. I mistakenly uploaded WP back to the domain root directory, overwriting the wp-config.php file for the 'yogaman_wp1' db (existing web site). Once I recognized the error, I corrected the reference values in the 'wp-config.php' file for the root directory. I uploaded WP v3.5 to the subdirectory 'wp2012' and changed the wp-config.php file for the subdirectory.
I could not log in to WP in the root directory. At the suggestion of my web host, I changed the user name and PW for the MySQL db 'yogaman_wp1' (web site), then changed the values in the 'wp-config.php' file (root directory) to match. What came up at my domain login page (http://lifeisastretch.com/wp-login.php) was 'Error establishing a database connection.
I checked various threads in the Support forum, and someone suggested renaming the folder /wp-content/plugins to '/plugins.hold' or '/plugins.1'. There was even a suggestion to disable all plugins through phpMyAdmin (I'm running v220.127.116.11)/wp_options/options_name but that function is not available to me. Should I just delete all the plugins for my web site and see if that makes a difference?
I checked my url for malware using Securi.net's malware screen, and it came back clean.
I have a help request in to my web host (GKG.net), and am waiting for their reply. Anything else I should investigate to resolve the problem?