How to deal with a lazy class? Imagine that you want to conduct your undergraduate classroom in a more creative way and introduce practical projects as a part of the final grade. However, students are lazy to embrace extra activities, and all of them decide not to deliver any report.

The department does not like the trouble of failing all students in a course because of an extra project.

What would you do to implement change when students are widely resisting?
Or as @JeffE suggested, How to deal with a department that does not give its instructors autonomy in assigning grades?

Additional Description: In fact, I want to change the grading system to reduce the weight of final exam, and add to small projects (e.e.g writing a one-page about the topic under consideration). The lazy class prefer to deal with one final exam instead of continuing homework. The school does not support this method, but they do not stop me as long as there is no trouble.
First things first: what did your syllabus say, and what did you say when you assigned the project?  If the assignment was a part of the final grade, and getting a zero on the project means that all the students will fail, and they knew this when the class began and when the project was assigned, and the project was assigned with enough time for them to produce an adequate result, then no one should complain when you fail them (or at least no one should have a legitimate reason to complain).  I have a feeling that if this is not a hypothetical case, there is more to the story.

I have been guilty of deviating from the syllabus in various ways over the years, but the students knew the ramifications of that deviation, and I was always fair in my grading because of it.  I find it hard to believe that an entire class skipped an assignment that guaranteed they will fail, unless of course it guaranteed they all receive an A.

I think you need to provide more information for a better answer, but the bottom line is that if the students failed the class legitimately, then fail them.  Just make sure you've got the means to back up your reasoning for those failures if it is indeed the entire class.