A charge q1 is placed inside a conductor and a charge q2 is placed outside the conductor.the charge q2 feels a force due to q1,but the charge q1 doesn`t feel any charge due to q2.why does this happen?what happens to newtons 3rd law here?

By the virtue of the property of conductor. Electric field produced by charge q2 is zero inside the conductor thus q1 charge doesn`t feels any force duw to charge q2. On other hand and induced charge is present into the conductor due to charge q1 placed inside the conductor which influences charge q2 due to its field.