What do you do when your teen is on drugs?

You need to take away her phone and money so she doesn't have access to buy them. Online school maybe good for her as well as getting professional help for her depression and drug dependency. If it's bad enough for rehab it may have to happen but if not maybe organising her to visit people in rehab or even institutions with people who have ruined their lives through drugs may be a good way to get her to wkae up.