I raised my daughter, 20, and, as a single parent, tried to do the best I could with her education. She dropped out of high school, recently took the GED, and found out yesterday that she failed 3 subjects. She now states how she feels like a failure and wants to harm to herself.
I told her I would take her to get whatever help she needed.
Your daughter appears to be having great difficulty in meeting the challenge of becoming a young adult and taking on responsibility for herself. She's struggled with school and now she's struggling with her feelings of self-worth.
Given that she says she wants to harm herself, you are correct to seek help for her immediately. Take her to the local emergency room for an evaluation, if you are worried that she may try to harm herself. Call the local mental health association, department of psychiatry in a medical center, or a psychiatrist on your insurance plan as soon as possible.
Explain to your daughter that you want her to be safe and to feel better about herself, so you are stepping in to get her the help she needs. A careful evaluation by the psychiatrist will see where she is with her mental state and will help to organize a plan to best take care of her.