Overwriting CSS 3.3.7 over 4.1.0

Hi,

I was using CSS 3.3.7 version to my mvc 5 razor application. I have updated it to 4.1.0 version through NuGet package manager but all my Menus and Style are broken.

Now, I want my CSS 3.3.7 back to my application because, I don't have time update all my style according to version 4.1.0. Do you have any idea how I can revert it back?

Thanks.