She can seek proffesional help(therapist,doctor etc...)And she should spend alot of time with friends to make her happy maybe that will help.And if she ever starts feeling down call someone immediatly.
And i saw how you put 14 year old girl and on your profile it says your 14 and your profile picture looks like a girl i guessing its you with the problem.Dont ever do anything stupid and seek proffesional help ASAP because mental illnesses are no joke and they can make you do some stupid things just be safe and i hope that you can some help.Just try to do things that keep you busy as i said be safe.