What happend when police took you.
get her FIR copy why they took you, so you will know her motive.
make police report that she left your hosue on D day, with her jewellary and child, it will useful later.
after getting FIR copy ask Police SP to do proper investigation, you can send letter by speed post and keep track and status with RTI.
and you can contact out helpline or weekly meetings if meetings are conducted in your area, they will guide you what to do.
meanwhile you can file Child visitation too.