I don't know what should i do with her..?help plzzz?

well one of our relatives has a daughter and she is 16 told me about her problem but i don't know how to help her,i'm not so friend with her:she has problems with her clmates and some of her friends at school,as she said she had many friends at school and they took advantage of her but she liked it in this way:for exp search for infos for one of her friends and even gave her DVDs to another friend but they never done such things for her,like one them always hide new DVDs to give her and the other never pad attention to her,so she is alone now and as she said she is getting depressed,one of the girls which lives near her is living there and she invited her for 3-4 times and aksed her to go out for fun but right now her friend doesn't pay attention to her,from the place i found she wants to enter one of the groups include her old friends that don't pay attention to her,i'm so sad for her and want to help her but i don't know what to do,she is agood girl what to do??