I agree with the previous responses- more information is needed. Consult with the counselor about the child's behaviors. Schedule a parent conference to learn if this has occurred prior to this school year. The parents may allow the child more control at home, which creates problems at school. Be firm about your expectations- stay in the classroom (safety), be seated, and complete the assignments. Praise the child for appropriate behaviors and work with the parents on improving behaviors.
I'm assuming you are a teacher. You don't provide any information on the age of this student but I assume you wouldn't allow a very young child to wander the halls (many schools would not allow ANY child to do so). Clearly this youngster is not motivated. You need to discuss this with the parents/guardians and see if you can pinpoint some of his/her interests. Try to demonstrate interest and concern for this student so he/she knows you are not the enemy. Depending upon the student's age, you might be able to explain the value of learning the lessons in the curriculum. Try to use his/her interests in designing some learning opportunities. Good luck!