Trackon Couriers — due in delivery

Address:

Patna, Bihar

I have send a Courier under courier no-[protected], on sep4 and the courier is not delivered till the 16th of sep 2017, who will be resposible for it.Companiy had told to me that courier will be delivered in 5 days but now about more than 15 days have been passed and courier has been not delivered.who will be responsible..?what will i do.?there is too much important documents in the courier..;What will i do..??