My boyfriends daughters mom has not seen her or tried to call her in 2 months and my boyfriend wants to get custody of her but the court said we need and address for her but we never know where she is at. When can you say its abandonedment? Like how many months can you say its abandonment. And the thing is she does drugs and sells her body on the internet she is not a good mother at all

Abandonment is merely a reason for filing for custody, and there are ways to file if you do not know where the other parent is, there will be requirements for searching for them, and for posting notification in paper pending court action. The clerk will not tell you how to do it,

You need an attorney for this.

You probably didn't listen carefully to what the court told you. Yes, I'm sure they said he needs to serve her notice that he is applying for custody. But there are multiple ways to satisfy the court that you have tried to serve her. So that's what you need to find out. How to satisfy the court that he has made a good faith effort to serve her notice of his petition for custody.