IIRC, dogechain works like blockchain.info's wallet and they let the user have the private keys, so if you have taken the back up you can import those keys into another doge wallet like multibit and use your funds.
PS: Can't access the website too, it shows a blank page.
But If cant login So how can I get private Keys ?
This is why you should have taken the backup when you first made the wallet or before depositing anything there. With cryptsy running, I won't be surprised if they have fled too.
Nothing you can do now but hope that its just a glitch and they sort it out soon and come back.