I'm 15 yr old girl and I have no one to talk to. Feel like there's no hopefor me :(?

It really sounds like you're having a hard time. You did say something about getting good grades, but you said it was sad. It isn't sad at all, the good grades will most probably get you a much better life when you are older. It opens so many doors and gives you so many new opportunities. Don't give up. I understand that you have no one to talk to. At some point in my life I felt exactly the same. I managed to talk to a teacher who I trusted and they got me a counsellor. I wasn't very close to my counsellor, but it did help me. You might not have a teacher you trust, but maybe try calling childline or look up some information about different counsellors in your area. If you're still not happy, I don't mind talking to you. I'm also 15 and lost my mum on my 14th birthday, after that everything just seemed to go downwards. Things have improved for me now, so don't ever give up :) There is always hope x