Sorry the page you are looking for has been deleted

I’ve just been a playing a little bit with a few themes, before switching back to my original theme.

To my horror, the home page now displays a “Sorry the page you are looking for has been deleted” message.

Any ideas what may have caused this?

The only things I have done in the past hour or so are:
i) Create a test post, then subsequently delete it
ii) Create a Private page
iii) Create a new page template called wall.php, which should have no bearing on the home page whatsover…

Eeek – help ??