Mamas of troubled teenagers… I need help

I’d like to know what advice you can offer as a teenager has ran away and is only 15 years old female. Doing bad in school grade wise, ditching, and almost getting expelled, and has now runaway with a boyfriend that is under the influence of weed pens and who knows what other things.. what do we go from here? What helped you overcome this stage? Not my kid but asking for help