Thanks for looking. What ever it was is gone now. It was like the CSS style sheet ( I may have the wrong technical term there – very rusty these days ) was not working. I should have taken a screen shot. Instead of the menu on top each menu item was on a separate line. It looked like this:
menu item 1
menu item 2
menu item 3
There was no two column layout. The second column was off the screen and I think way down on the bottom of the page. I used google to find another Twentytwelve blog and it was doing the same thing as mine. I filed a bug report with Firefox. When I checked the next morning it was working again.
Thanks for looking.
I should have marked it resolved, Did that now.