Hi,
The screenshot indicates that the CSS from HikaShop is missing.
I could be that you had a PHP fatal error during the generation of the page, preventing Joomla from adding the CSS files to the page.
Normally, you should be able to see a "fatal error" message at the bottom of the page.
Do you see any ?
Also, you can activate the "debug system" setting of the Joomla configuration and try again. This might help displaying the error message at the bottom of the page. So please try it.
Once we know the error message, we'll be able to tell you what to do.