Indian Railways — Failure to retrieve my luggage

I was travelling by Shatabdi express (NJP to HOWRAH) train no 12042 in coach no C3 ( seat no[protected]. After I reached Howrah station, unfortunately I left a bag in the coach . By the time I realised, the train already left for NJP station . I have valuable items and cash. Need serious help. The station in charges have no contact number to connect with the train officials.