Struggling to engage a student

We are struggling to engage a student, she is refusing all work and to go in any classrooms including working with staff.

She will not do work in a separate room, garden, with staff, by herself or with favorite staff. It's a big no from her. She won't even go into the classroom to listen to see what she will be learning. She is more than capable of the work. 

When she has been in the classroom, 2 times so far, she has been slightly disruptive, talking, butting in, raising her voice, standing and climbing on furniture. There is only 2 other students max in a classroom (3 including her). When she has done work, once, it was maths and she would answer with such sarcastic answer such as, not my problem, I don't know do your problems yourself and so and so. 

When she is not in the classroom or doing work, she is swearing, shouting, refusing to follow any instructions, not engaging with any staff, ripping display boards, screaming, you name it. 

She will ask to go for a walk and will then have a vape when she is away from school. She seems very low, angry, not interested or motivated. Recently she has asked to go home throughout the day but we have managed to make a plan to make the day easier so she stays. Today she didn't and went home early afternoon. 

She is refusing to communicate what is wrong, we've tried everything that usually works and we get no response. Nothing comforts her which used to and now she will not let anyone touch/comfort her through side hugs or rubs. 

If anyone has any ideas to help, that will be very much appreciated. Thanks in advance.