I have posted about my daughter before & this is obviously just my experience, but here it goes.
My 19 yr old daughter flunked out of college. Too much partying not enough grades. She was a high school honor student. She moved back home. Slept all day, worked evenings, partyed til morning. After months of this and asking her to please call us & tell us when she would be home, we gave her an ultimatum. Call, follow the rules or you are out. She didn't follow the rules, stopped coming home. We tried calling & texting. We texted her that her stuff was packed & on the front porch. Several days later I came home & it was gone. But we had no ideal where she was. Couple of months later one of our high school sons heard where she was staying. It was the local party house & family. I went there & told these people what they were doing was wrong. That week we went on a search for her car. Hours later we found it, took it, & hid it. It was the car we gave her when she graduated high school. It was in our name & I didn't want the ramifications if she was driving drunk. Things progressed worse.
Finally we did our own intervention & tricked her to my sisters house by promising her car back. We gave her a choice. Rehab or never see or speak to us again.
She went to rehab. 30 days. Then she went to a sober living facility for 90 days.
She is now a self sufficient & beautiful adult. Her only problem is trying to find a stable man in his twenties who does not "party". But she has her values & won't except anything less. I am proud of her.
I do not regret putting my foot down. She expected it. And it did get worse before it got better. But I did not give up my values.
The girl (& her family) that she was living with had a major wreck & totaled her car just weeks after my daughter went to rehab. Shortly afterward she left her home & is now living on the streets.
A few months ago her sister told my son...." I hear your sister is doing great". He said yeah. She said "That's great my sister is still an addict".
I know it's not that simple. I am lucky. But I'll never forget when I approached those parents & told them this was all wrong. They said..."what you going to do about it, they are over 18"!
I had to at least honor my values & those that I had raised her by. And if that didn't work, then so be it.
Good luck, my thoughts are with you!