Insoluble problem with Magento newsletter

Hello together,

I have a really insoluble problem with the newsletter in magento. A friend of mine bought a shop with a custom theme and there is no newsletter. So I went to the admin area and set it on everywhere but in the frontend it does not appear anywhere. My first guess was that the code for it was missing in the theme but it's there. Even extensions won't solve the problem. How do I make the newsletter field visible in the frontend? I am very thankful for help. I tried it now over 2 days but didn't find any solution.

Best regards
Moritz