if you were seeing logs previously on this same server, and now you are not, it suggests to me a problem prior to loading of ZC.

did you make any changes to the .htaccess file? and the problem is only in the admin? did you look at the troubleshooting listed here:

https://www.zen-cart.com/content.php?124-blank-page

the error is almost probably in the apache log (assuming the server uses apache to serve up web pages). so try and get access to that and see if that provides any clues....

there are all kinds of troubleshooting methods available prior to just taking stabs in the dark. personally i do NOT think its a database issue but i have been wrong before...

good luck!