I'm really not sure what might have caused your problem but the fact that certain required configuration options were missing from you gallery XML files seems rather strange (and, as far as I can remember, I've not seen it before).
Re-saving your galleries seems to have reinstated the missing configuration options (I now see them in your gallery XML files) but I notice that your galleries still do not display.
It looks like there might be a problem with the plugin's 'config.php' file on your web server.
The file might be corrupt or incomplete or the script might use a PHP function which is unavailable or disabled on your web hosting account. (WP-SimpleViewer requires PHP v5.2.0 or later.)
It sounds like you have already tried re-installing the plugin so I'm not sure what to suggest next.
I would be happy to investigate further but, in order to do so, it would help if I had access to your web server and WordPress site.
If you are agreeable to this, then please let me know and I will send you an email address where you can forward me your FTP login details (host, username and password) and WordPress login details (URL, username and password). Once I have access to the WP-SimpleViewer files on your web server, I should hopefully be able to determine the cause of the problem and propose a fix or workaround.
SimpleViewer Support Team