How can I recover a missing BTC from a correct transaction and who is the responsible for it? today I withdraw 1 BTC from my account at Gatecoin exchange to be sent to CEX exchange. I got the BTC address from CEX and created the withdraw address for my withdrawal. I proceed with it and it took 30 min approx to be confirmed by Gatecoin and then waited 1,2,3 hours and nothing was arriving in CEX. I got worried and checked the Gatecoin link for blockchain transaction and for my surprise NO Transaction was registered there!!

OMG! went back again and again to both exchanges to see whether the BTC was back, but not at all. My BTC is gone and disappeared. No trace in both accounts Gatecoin and CEX. For the worse, not even the Blockchain has a record of it? Seems vanished. Gatecoin confirmed the withdrawal after 30 min. and once open the transaction link, nothing was found in the Blockchain!

How can this happen? Is Gatecoin responsible or CEX? 
Anyone having similar experiences and would like how to resolve them?

The terrible scenario is that both Support Departments don't answer any query as they are overloaded with the great demand from new clients.

I have already reported to both exchanges but now how long and how this is going to be solved?

I will appreciate some feedback from you guys. Thanks in advance.
Without your tx id it is hard to tell what exactly happened but usually you don't need to be worried. Your described scenario sounds like a "miner fee too low" issue, the transaction gets broadcasted successfully, thus Gatecoin or any other exchange believe the funds are out of their system, but then got pushed out from the mempool because other transactions have a higher fee. Such issue usually fixes itself once the fees on the network/mempool go lower. The transaction will be automatically re-broadcasted by the bitcoin node of the exchange and then gets included in a block and you get your coins on the receiving address.