That happened to me today as well. If you're looking for the cached page, click the green triangle after the URL.

When doing a Google search and moving the mouse cursor at the right hand side of each listed heading the ">>" symbol will show, pointing to this will show a preview of the site, not any more. I don't have this facility any more, I deleted the cache contents under tools but that didn't fix the problem. I wish I could take a picture to show what I mean but the ">>" symbols are gone!

I remember them well. I do not see them in Firefox or in IE right now. Google changes stuff regularly. Often they are just experiments and change back. If you want to check with Google, the search forum is here: https://productforums.google.com/forum/#!categories/websearch

Here's a thread from Google's forum indicating the previews have been discontinued: What has happened to Google instant page previews? - Google Groups.

Thanks, what a pain though, I always used it, I think there is an add-on somewhere that displays a magnifying glass symbol, will have to try and find that!! Again thanks, Reece.