On the add-ons overview page you can find the "Advanced" button (if you have the necessary permissions). By clicking on it, an additional area is displayed. There you can select to reload modules, templates and language files. That means, WBCE CMS resets the information about the selected add-on type(s) in the database and synchronizes this information with the data from the file system.
This can be necessary if you applied changes to modules, languages or templates via FTP or in some cases after an update of the WBCE CMS core. So if you're missing some modules or any other issue with modules, templates or languages exist, try to reload them here.