文件夹的位置已更改,但现在没有任何作用

I moved the images and js into their own folders, typed "..\folder_name ame.jpg" in the PHP file but those which I used them in the background doesn't appear on the screen. And the whole screen except the texts is just white :-/ I type w3-blue on a container but it is just white. the links in the head are fine. the only thing I changed was the folders and the location of the folders in the PHP file.

.image-container-ebook {
  background-image: url("..\project\image\20.png");
  background-size: cover;
  position: relative;
  height: 350px;
}
<script src="..\project\js\mysearch.js"></script>

This little code was working before. Do I have to add something more? and please also help me out with a javascript and PHP files. There is a modal I use to open for Login written with PHP but when I open it now, it says that it can not find a file but the location is fine. this is how it looks now