I know you would like an answer as quickly as possible. But there is an unusual quality to the story of your daughter. And so I need to ask more questions to give the best answer for you.
What do I mean by unusual?
She isn't using drugs or alcohol but has no seeming capacity for getting along in the world. That is very unusual EXCEPT if there is some developmental problem:
Is she developmentally challenged? For example, very low IQ?
Or perhaps Asperger Syndrome (Autism
spectrum type disorder). Here are some questions to help identify this:
Has she been evaluated as being higher than average intelligence?
Does she make friends easy now and in the past? Did she always play in age appropriate ways and does she have good social skills?
Does she tend to obsess on activities she likes and have a hard time stopping when it's time to do something different?
Does she have repetitive motions and movements? Does she also have certain habits she does over and over?
Does she bring his fingers to his mouth or make facial expressions when talking, when she's unhappy or angry?
Does she have a hard time relating to other people's feelings?
So, if none of the issues above apply to her, what are the mental health issues that you referred to in your original question? What we've discussed so far is extreme lack of motivation. Is there some underlying mental health issue that was diagnosed to account for this?
If so, what treatment did she receive? How did it go?
Any residential hospital will need her cooperation. Would she be willing to go?
I know these are a lot of questions. But as you can see, she's had a very long-term situation that has not changed over time.