Installation problem with existing WordPress website

I set up a test WordPress website (to replace an html website) and used the standard 2012 template for the initial setup.

To give the website more style, I bought and installed your Highend theme. However, when the Highend theme is activated the page navigation disappears and more importantly so does the entire DASHBOARD so I can’t see anything when I try to update the content.

The test site is at – http://www.applebycastle.co.uk/AC/

I have uploaded the Highend theme several times (including one file at a time) so all the files should be there.

I will give you FTP access info if you email me.

Thank you.