Mainly, it depends on your school. For many colleges and universities, the answer is a flat “no.” You must live with your choices and try to improve your GPA by doing better in the future. But some schools will allow you to retake a freshman-year class to improve your grade. Some schools limit this to one class, while others do not have a limit. Usually the new grade will replace the old grade, but you will not earn any credit hours for your second attempt at the class, and in many cases the original grade remains on your transcript though it is not part of the GPA calculation.
Sometimes teachers make mistakes, which is why it is important that you are able to calculate your final grade in a class on your own. You will need a complete list of your grades in each weighted category of the class in order to accurately compute your final grade. These categories most commonly are homework, tests, and quizzes. Sometimes teachers use special projects or class participation in addition. Computing your final grade consists of finding your average in each category, then multiplying it by the percentage of the class it’s worth and adding all the adjusted categories together.