OpenX User Interface can be disabled in situations to prevent users from logging into the OpenX installation. In this situation the server only delivers banners and ads that are already created.
However, OpenX User Interface could be disabled by mistake and after that login will not be possible. The only way to re-enable OpenX User Interface will be possible by editing a configuration file.
*How to re-enable OpenX User Interface
1) Go to '\var' folder in your OpenX installation
2) Find the configuration file, e.g. 'www.mysite.com.conf.php'
3) Open the file for edit and find section with:
4) Make changes to:
5) Save the changes
So with these steps you will be able to re-enable OpenX user interface if it's disabled.