I'm not sure what this means. I think it means that you still have the private keys for wallets in cold storage, but just don't have any account / trade data since the last backup. If that's the case, perhaps the right way to deal with this is:

(1) start with the last backup

(2) measure deposits / withdrawals since the last backup, based on blockchain data (surely you at least know the static addresses involved)

(3) apportion the net difference between accounts based on the verifiable deposits and withdrawals of each user since the last backup

Let's say for simplicity that there's 10 BTC in cold storage for all of Atomic Trade, and total deposits since last backup were another 10 BTC. If my user account balance 2 weeks ago was 1 BTC, and I deposited 1 BTC since then as verified on the blockchain record, I would receive a total adjusted balance of 2 BTC.

This really sucks though. I would expect to see a more active approach to M$. I'd be happy to help with a demand letter, etc. If you don't have any funds in cold storage offline, though, I would just say don't do anything crazy!

Z