Unless you got a ZER0 on EVERY test; I'd have to say it is impossible to end up with a Zero.
Considering you said"
but i was always close to average in the class...
I'd guess he screwed up badly. I'd be taking my test scores to the Dean and be asking for an independant evaluation. Maybe this prof screwed up the whole class. Do you know anyone else in the class you could compare grades with?
you should see this guys reviews on that site... unfortinuetly he is the only prof that teaches this course at OU for now. we shall see though, the entire class signed a petition asking the math department to hire a different prof to teach stats.