You can find the following error when you try to switch the layout or apply sorting in the console log of your browser (i.e. hit
F12 in your browser):
Mixed Content: The page at 'https://www.discountirrigation.com/electrical/cable.html' was loaded over HTTPS, but requested an insecure XMLHttpRequest endpoint 'http://www.discountirrigation.com/electrical/cable.html?mode=list&ajaxcatalog=true'. This request has been blocked; the content must be served over HTTPS.
This means, that your store was loaded via https (secured connection), yet the ajax call that is handling the the troublesome actions was called via http (insecure connection).
When setting up a Magento store properly to run on https this however should not be an issue. The fact that your store is reachable over http AND https makes me believe that there is an issue in your setup.
The easiest way to address the problem might be to change your
Unsecure URLS in
System -> Configuration -> GENERAL -> Web to
https://www.discountirrigation.com as shown in the example screen below.
After applying that change, make sure you clear all your caches.