Bad score

Last week, I took an exam of HSC. The score was so terrible that I could not even believe my eyes. This is the worst mark that I had got. I did prepared before the exam. Thus I did not expect that the result would be so horrible. What is more, I am planning to transfer to another university in Boston. Expect the grades that I got before, the mid-term points would also be considered. That's why I am so worried about the score. I am considering whether to withdraw or not this class.