Bad grades (long one)

I’m a 17-year-old female and a junior in high school. My grades have been poor since last year, which is when my social anxiety increased. I often receive F's and D's because I’m afraid to ask for help. I don't want people to think I'm dumb or unable to understand high school concepts. So I try to get everything done on my own.

Recently, my mom threatened to tell my dad (who is divorced from her and with whom I don't have a good relationship) to take my phone away from me and ground me from hanging out with my best friend until my grades improve. It feels like basic parenting stuff, you know?

Anyway, she went on this long rant about my graduating, and she started crying, saying she doesn’t want me to fail in life because I don’t pay attention or ask for help. I tried to explain to her that I’m struggling, but she just tells me to ask for help, even though I've tried to express that it's difficult for me to do that because I'm struggling all around. She doesn’t really listen. How can I make her hear me?