Overturning a grade is it possible?

I have been failed in a nursing program. I believe I had a good reason to overturn my grade so I filed a grievance with the school and they would not overturn it. They told me that because it has been over ten weeks since I finished the class they cannot overturn my grade and that is written in their policy. I don’t want to have this F on my transcript. So if I have a good reason to get it overturned I am wondering if I am being given false information? I am thinking about suing the school but i don’t know if a judge could force the school to override their policy. The only reason why ten weeks have passed is because the grievance process took many months at the school so it is not my fault that this much time has passed. I don’t want to waste my time suing the school if it will be pointless and I will not win.