My 14 year old daughter refuses to come home?

i have had sole custody of my daughter since i split from her father 9 yrs ago.he hasnt bothered with her for years but i insisted that she go and see him in the last holidays. he brought her back last week 3 days late. he has now taken her without my knowing. he refuses to let me have his address. i have tried online electoral rolls but nothing. does anyone have any advice i am at my wits end