CSS and JS not taking root folder

Hi, my website’s cdd and jss are not working.

. How to define this website_css_url. Previously it was working but now it has stopped working.

whenever I take the backup and put it in another folder. it starts to work but after few days, css and js stops working.

I am not a coder, so please treat me well.

How do you include the files in your head?
In CakePHP, what I generally do to load local CSS is: <?= $this->Html->css('/assets/css/whatever.css'); ?> and <?= $this->Html->script('/assets/js/whatever.js'); ?>

when that loads in the browser, it translates to: <link rel="stylesheet" href="/assets/css/styles.css"/> and <script src="/assets/js/whatever.js"></script>

You can read the documentation regarding that here.
If it stops working all of the sudden, then you or somebody else might be moving it around?