Functions not working in child theme

I used Zerif lite to create my website, and decided to upgrade to Zerif Pro. Also i decided to start using a child theme when I had to change the theme anyways. My problem is that some of the functions from the original theme has stopped working.
I uploaded the stylesheet.css, the index.php, the footer.php and the front-page.php.
Firstly, the images in my ‘Our focus’ widgets are not displaying. I tried replacing them several times.
Second, my contactform at the bottom stopped sending me emails when the form is filled out.
Can someone tell me what I did wrong?