It gives me the courage

Since the start of the 2nd week of classes, i noticed something. I notices that i can't remember some things that i used to study and apply before.Particularly in mathematics, last year, i like to solve problems, create shorter formulas, prove things using postulates. But now, i am wondering why i felt that i don't know anything about that subject. Like I am just a child learning to count. Since the begining of this year, i get low scores in that subject. But that doesn't made me weak, instead, it refresh me and let me start doing it again to recover the one i knew before.