With the style.css, we are mentioning like that the theme is a child of some existing theme. So the css file is enough to render all parent theme functionalities.
We are using all other files to add or alter the existing theme features.
we have to include the following basic things in child css file
/*
Theme Name: Your Custom Theme
Description: The simple and powerful theme.
Version: 1.0
License: GNU General Public License v2 or later
License URI: http://www.gnu.org/licenses/gpl-2.0.html
Text Domain: twentyeleven
This theme, like WordPress, is licensed under the GPL.
Use it to make something cool, have fun, and share what you've learned with others.
*/
You first remove all files in child theme except the style.css and check whether the default theme features rendering or not.If no, then it is the problem with our style.css.
Also, if any custom css / js file needed, it is better to create them in a separate folder within our child theme itself and call them through our child functions.php file.
Please give us the code that you made in style.css and functions.php