My websites layout suddenly stopped showing

Hi

I am not sure what I’ve managed to do, but now when I look at my (or my companys’) homepage, some elements are not loading. It’s as if it doesn’t read the CSS-file and all the customizations I’ve made. I’m starting to freak out as this is my running companys webpage and I cannot seem to find the problem!

Please, try to help me if you can. I have a back-up from last month (but it is at work and I am currently at home) where I just copied the wp-content folder and all subfolders, but can I be sure that it will reset it to the state it was then?

I hope you have some time to look it up if that is a common problem that you have seen before. Thanks in advance