Can access wp=admin but can not access or preview the website

I am working on an online store where the store has nearly 2000 products already updated in the website. I did make some changes t the css and another file called single-product.php which is the template file for displaying single products. All of a sudden the site got vanished and it is not loading at all. Here is the link for my website. I have changed back the files that I edited to the same way as it was before. But still I am getting the same that the website is loading but it never loads. Please help me what all I have to check and what is the solution to get my site up and running. Thanks in advance.