I'm starting a new website based on the Galeria template. So I started modifying the demo content.
When I changed the content of the menu-item "K2 style -> K2 - category view", the items weren't shown at all. No problem, you should say, replace it with the original settings. But that's impossible. Whatever I try I, it isn't working

This is the original setting, which I can't get back:

index.php?option=com_k2&view=itemlist&layout=category&task=category&id=15

Hope you can help me.

Live Url please

Please rename the folder and try again
templates\jp-galeria\html\com_k2
to
templates\jp-galeria\html\com_k2_org

This solved it. Thanks!

Problem solved.