Why do I feel lifeless and empty?

Ever since this year started, I just feel dead. I stopped exercising, trying, or anything really. It all feels pointless all of a sudden. My grandparents both passed away this year, around the same month. But I think even before this I started to feel a little empty, it just keeps getting worse. I didn't go to practice, don't feel like going to school, scared of socializing, and easily irritated, and I just want to go on the computer all day or do nothing but listen to music. I feel so confused, I don't know what to do anymore, I just feel broken because this school year was pretty harsh for me. I don't know how to explain it to my parents because they'll just call me crazy and brush it off. I'm scared to get therapy because I doubt my parents will let me, since what they see outside of me is perfectly fine, but I'm deeply troubled on the inside.