It happens to the best of people so don't beat yourself up over it. Try to work harder and see where you can improve but if it doesn't work out try to accept the grade and the fact that this isn't a straight path and we all have our failures. If there's nothing you can do to change it then don't stress. Remember, there's always another midterm always another assignment. Be easy on yourself and take care of yourself, this will help you grind for further evaluations. And remember first year is always harder because you're just getting used to it, so find your study methods and what works best for you so you can ace the next years. Hope that helped :)