
You are going to need to provide more information; I see no reason why the manager would be blank while the front-end seems to work just fine. Perhaps this server is running tomcat and there is a conflict with the directory name, ’manager/’?

Not easily; the directory name is currently hard-coded in too many places in the 0.9.6 and previous releases. Starting with the MODx 0.9.7 release however, every directory in MODx will be configurable at install.
but can I change de directory name?