My daugther is 17 now and has a baby she hasn't been in school since she was 12years old. The order was done in 2005 whe I was leaving her mother but I didn't leave till 2007.what do I do they are getting me for back time since 2005 when I was still living with my family?

So in 2005 why did you not appeal or ask for a modification ?

The fact is, if the child was living with you and not the mother, if you did not go and get the court order modified you are obligated to pay the court order.

Is the 17 still living at home with her month ?

Having the child may allow it to stop in some US states, in others it will not, but nothing is automatically, you have to go back to court to get it to stop