CSS file not showing the design on website [closed]

So, basically I have a CSS file. It works perfectly but after coding for a bit and I change here and there in CSS file and it doesn't show any changes I make in CSS file on the webpage. But, if I copy the same code in different css file again and not change anything inside the file except change the file name (like previous it was style.css and now changed to styl.css or anything) It works agains fine.

I am not sure why it keep happening over and over. Is it a bug?

Thanks. Any help is appreciated.