iphone locked

hi id given my niece my iphone and only few days ago the find my iphone was activated on it and locked the phone but it keep lookin for a apple id, her one is linked with the fone but its lookin for another apple id that we have no clue to whos id it is the phone is not stolen as i bought it from new and she doesn know the apple id email address that its sayin its locked to is there any way of gettin it unblocked from that id or what can we do thanks