Gopi, I did as you say, and I have an interesting result.
I was logged in as admin when I checked the modified header.php.
It gave me what I wanted, menu is below the header image.
However, I then checked it on a second computer I use to see a page as an unlogged in user would see it. The menu is back on top. I downloaded the header.php file, just to be certain that it somehow didn’t get changed, and it is as you said. The header code comes before the menu code.
The position of the menu is dependent on whether I am logged in or not. How can that be?
No chance for this. because we are moving the entire menu code after header part. i think its a cache issue. if you are using any cache plugin please clear the cache (also clear browser cache) and try again.