Well, give a try on this freeware for data recovery: http://www.freenew.net/windows/icare-data-recovery-software-45/68220.htm
it is designed for restore lost data due to deletion, format, and many other reasons, u can preview the files before restore. But the time will be very long for it sounds that the data u need to recover are quite large. BTW, it can only retrieve 1GB for free, but with its help you can at least make sure whether the data are recoverable. Hope it can indeed help u.