Its an older movie where a young girl lives with her dad and he's a drunk I think but he sends her to school in the same clothes that she pees in and she won't talk to anyone and she's wild (i think she has red hail) so as time goes by the teacher gains her trust and helps her gets her to talk and act like a normal kid and at the very end she on a school bus going home I believe and the teacher tells her "i tamed you"

Sounds like One Child (http://en.wikipedia.org/wiki/One_Child)