The plugin does not have a valid header.

Try to see if using a default theme helps.

I guess I don’t understand, I really don’t want to change the looks of the site, or can I revert back without any harm to the original theme?

If you changed to a default theme we can determine if its the theme or if it’s Jigoshop. You can always change back. It’s just some themes don’t play nice with Jigoshop.

OK, it installed with the twenty thirteen theme, but the cart does not work, you can put products in it, but the page for Cart just shows the word cart…

One could see it here: https://empirexdata.com/tst/shop/

OOps, found an issue with content custom template causing jigoshop content to not show..

Thanks for fast response

Glad you figured it out.