How to reset fullscreen slider height?

Hi,

I am fairly new to WordPress and based the homepage of my website on the enfold demo’s “one page portfolio”:

I wanted to change the height of the fullscreen slider, so I did a search, and tried the following things out. The responses from which I tried out code were these:
https://kriesi.at/support/topic/reduce-height-of-fullscreen-slider-in-responsive-mode/#post-169700
https://kriesi.at/support/topic/reduce-height-of-fullscreen-slider-in-responsive-mode/#post-169720
https://kriesi.at/support/topic/reduce-height-of-fullscreen-slider-in-responsive-mode/#post-170237
https://kriesi.at/support/topic/fullscreen-slider-change-the-height-of-100-to-100-100px/#post-178039

None really worked, so I decided to go back to square-1 and replaced the files I had modified with the original files from the enfold and enfold child theme downloads:

/enfold/css/custom.css
/enfold/js/shortcodes.js
/enfold-child/style.css
However, even though now the original files are there, the site does not show any pictures in the sliders anymore. Any idea how to get them back to functional?

(I am using the enfold child theme.)

Thanks!
Eric