Were the instructions "do not use a computer solution" specified ahead of time? If this was either in the syllabus or otherwise discussed, then it's your bad,

Were the instructions "do not use a computer solution" specified ahead of time? If this was either in the syllabus or otherwise discussed, then it's your bad, and you have to eat it. Otherwise, it's outrageous that rules are made up on the fly, and you should appeal to the professor. Appeal to the professor first; don't go over his head. Your argument should emphasize fairness: rules are being made up on the fly. Don't print out your homework in a font of your handwriting. You won't fool anyone, and you'll be rightfully nailed for quibbling.