Don't give up hope. If the prof. is generous enough, he or she may be willing to work something out with you, maybe do something else to make up all or part of it. Dosent hurt to beg and plead at this stage, at the worst he/she will say no.
I missed a physics quiz, I overslept, fortunately the prof let me retake it. I did badly on it, but at least it was better than getting a 0.