Serious question about my little sister?

I need a psychological diagnosis of this girl lol. Like she is just weird, she is 14 years old about to go to high school, all she does is stay on the laptop 24/7 and i mean literally. She wakes up doesn't even brush her teeth, doesn't change clothes, she just goes straight on her laptop. She doesn't like to take baths either, my mom has to force her, and when she goes in, she'll be inside for 2-3 hours in the bathroom doing who knows. She doesn't care about her appearance like most girls her age, and doesn't really make friends that well but she does have a few. She just spent 15 minutes crying loudly because my mom took her laptop away, and I know soon she is going to be begging me for mine. I try to talk to her, and help her find other interests but she just doesn't care about anything else. It's like she lives in her own world. Why do you think she acts like this? What goes on in this little girl's head lol?