I am really worried and depressed?

I constantly get anxious and depressed about getting good grades. Before this, I never had to worry about anything because I was always a good student, but this year, I find myself lacking, not in how good I am in studies, but being responsible and doing homework on time, completing it, things like that. I am worried that my parents will be dissappointed with me, because they never had a reason to before. I am trying to fix myself, but I WILL NOT tell my parents about this, so can you tell me how I can be better, please? I really need help.