I failed my final exam, and I failed the cl?

So I just took my math final and I totally failed it. I blanked, I really don't know why because I knew how to do it! I just completely blanked and I failed it. I'm a bit confused though, I had an A- before (93.5%) and I failed the final with a 52% and my final grade is now an F. i failed the cl! i didn't think a final was worth that much. Does it seem like the final was worth to much? Or do you think it was like a typo or something? Like should I go talk to him and see..?