I was however able to get back approximately 2/3 of the differential data from the drives using some recovery software and specifying the date range from the last backup to the day before the virus infected the system. My preferred choice of recovery software for windows is Active Undelete.
The software is very intuitive, reasonably priced and has helped me recover more files for clients from accidental deletion, dead hard drive or an accidental format. I ran a full drive scan, took about 6 hours through USB 3 on a laptop to recover the differential data. Of that differential data 80% of the data appeared to be uncorrupted,usable and accurate as of the day modified.
I will be doing a follow up post on this for a backup solution that is ransomware resistant to with-in 24 hours from the time of the infection. It really is a post you don't want to miss.
Cisco did a very good blog post on the technical aspects of cryptowall 3.
Here are some links on the very first type of this crypto-ransomware cryptolocker.
The TWIT network did a great breakdown on cryptolocker on Security Now!