Well, a suicidal person may not ask for help, but that doesn't mean that help isn't wanted. Most people who commit suicide don't want to die, they just want to stop hurting. Suicide prevention starts with recognizing the warning signs and taking them seriously. You might be afraid to bring up the subject, but talking openly about suicidal thoughts and feelings can save a life.
It's obvious that something is wrong with your friend and the best way to go about this is to have her confide in you. Don't force her to speak about her problems but let her know that you'll always be there for her and that she can trust you and tell you anything. When speaking to this friend though, don't:
1. Argue with the suicidal person. Avoid saying things like: "You have so much to live for," "Your suicide will hurt your family," or “Look on the bright side.”
2. Act shocked, lecture on the value of life, or say that suicide is wrong.
3. Promise confidentiality. Refuse to be sworn to secrecy. A life is at stake and you may need to speak to a mental health professional in order to keep the suicidal person safe. If you promise to keep your discussions secret, you may have to break your word.
4. Offer ways to fix their problems, or give advice, or make them feel like they have to justify their suicidal feelings. It is not about how bad the problem is, but how badly it’s hurting your friend or loved one.
5. Blame yourself. You can’t “fix” someone’s depression. Your loved one’s happiness, or lack thereof, is not your responsibility.
If she doesn't confide in you and she isn't getting better then you should tell someone of authority. Perhaps a guidance councillor could help. I know she might feel betrayed but it's what you have to do if you want to help help but you have to be careful, because this could either push her to the limit or save her and the latter one is what we want to do.
Look out for physical signs, like cutting or anything else. I recommend that you always compliment her. Tell her she's pretty, or she's smart, that she's unique and special. Let her know that the world needs her, that you need her. Tell her things she never hear. Just always hug her, randomly even and tell her that you're proud to call her your friend and that she's great. Let her know that her opinion matters to you. Do the best you can but whatever happens, know it's not your fault and that you tried.