Likely it will just lower your grade. It depends, though, on a lot a factors we don't have.
How big is the school?
How much was the final weighted?
What is a passing grade?
How is your A calculated? Which sounds like the second question. It's not.
If you are in a K-12 school, the administration would be hard pressed to make you retake the class. To do that it would likely throw his entire timetable into chaos. A much bigger school wouldn't have that problem.
Even if I had all the answers to the questions above, it still might be impossible to give you an answer. Only your teacher really knows. Think about asking her / him.
