Edyta wrote:
And I actually don't know when exactly the problem appeard. I recently updated Joomla to newer version (2 or 3 times).
Maybe I'm reading too much into that statement but when you FIRST installed it could you manipulate the RokSprocket module settings?
If so it probably is an extension or plugin that you've recently added.
Try this, backup your site with a free copy of
Akeeba backup
then in the
Admin -> Extend or Extensions -> Extension Manager -> Manage select the DISPLAY to ALL. Then uninstall every item that doesn't say Joomla Project or Rockettheme. If RokSprocket works then it one of them.