I screwed up the final. What should I do? I'm a master electrical engineering student in a state university and I just took my very last final exam on Wednesday. I totally screwed up. I could not solve any of the problems (4 problems). It has never happened to me before. I thought I studied enough for it but I guess not. I'm looking at like 20 on the final which is 35% of the total grade. I had about 80% before final. What's sad is that I did study for it and I feel crushed that I couldn't do it at all.
I had a 3.5 GPA before this. Since there are only 10 classes in masters, if I fail 1 class would be fatal to the GPA. My main concern is I'm about to graduate and look for a job, but this is going to ruin my GPA. I sent an email to professor yesterday saying:

I know I did very poorly on the exam. I thought I understood the material and would be able to perform similar like the midterm but clearly I was wrong. I spent a lot of time doing homework and study but I really don't have excuse for this kind of performance.
Would you please consider withdrawing me from the class if you are able? I really can not have a D or F. . . . I understand this is my own responsibility and thank you for the semester.

I sent it Friday 9 am. Of course, I haven't heard back from the professor. My question is: should I just wait for the grade to show up on Wednesday next week and see what happens or go talk to the professor?
As Nate Eldredge cautions in his comment above, it's probably up to you, not the instructor to submit a withdrawal request to the registrar.  Usually, the instructor's only involvement is to approve or disapprove your request.  But once you've taken the final and depending on your school's policies, it's probably too late to withdraw anyway.

That said, your life is almost certainly not ruined. If you wrote anything at all, you will likely get some partial credit.  And who knows how your instructor will curve the results.  If you had trouble even after doing your best to prepare, it's quite possible others did as well and that the curve will be much easier than either you or the instructor expected.  Sometimes instructors accidentally write a test that's too hard or has errors that make a problem impossible.  (I taught EE at Washington and now teach CS at Michigan, so think about how I would know this happens! :)

Finally, even if your final grade is low enough that you need to repeat, this is still not fatal.  Students are rarely aware of just how many of their peers have to repeat classes.  And guess what, they still get jobs.  Yes, of course I understand why you're upset.  But you're not dead yet.