Header image won't display after upgrade

I'm using WordPress 3.5.1 and to Atahualpa 3.7.11 theme.

On my site, the header image at the top won't display. Instead, I got a generic image of a white flower. After messing about, I get a different default image, BEHIND my semi-transparent blog name.


FileZilla shows that my header image is still in this folder:

/wp-content/themes/atahualpa/images/header/banner-image.png

There is only one file in this folder.

I'm unable to solve this. I need help.

Please offer suggestions. Do assume I know nothing, so if you add details and context in your reply, that's better for me.

Thanks.

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I did this:
It suggests my custom banner image got removed by upgrading. I see the file in FileZilla, as I described above, and I can view it manually—it's my custom banner image—but it won't display on my site. Instead, I get a default image.

What folder via FileZilla do you see the image in?
What folder did you install Atahualpa 3.7.11 in?
Do you have a link to your site?