Thank you for the reply jumper and jaclaz! Did not realize the board do not send out email to notify me of any thread reply. Will check more frequently now. jumper: both hard disks were used on x32 system (Windows home server OS). The 4TB hard disk went raw when power was interrupted on the x32 home server, and the 2TB went raw when I plug it into x64 (windows 8) machine using USB bay. jaclaz: i will download testdisk and give it a try, before that, let me give you the problem report... Describe in detail your environment (running OS) 4TB drive: it was a backup drive that I plugged into the Windows home server as a backup of some files. It changed into RAW in the Windows home server setting. 2TB drive: it was part of the data pool in the Windows home server. It changed into RAW as I plug the hard disk into Windows 8 x64 machine using a USB bay. how the disk(s) were partitioned (as far as you can remember) 4TB drive: i remembered this one, the drive was formatted in a windows 7 x64 machine as NTFS in 1 big partition of full volume. 2TB drive: i do not fully remembered this drive, but it should be a NTFS system previously, either formatted by the Windows home server or I formatted it on the side in windows 7 x32 machine as NTFS in 1 big partition of full volume. the exact make/model of the disks 4TB drive: Seagate desktop HDD, 4000GB @ 5900rpm, Model ST4000DM000 2TB drive: Hitachi deskstar, 2.0TB, Model HDS5C3020ALA632 So, the 4TB was being used to backup some files on the Windows home server (WHS), and power interrupted the the hard disk turned into raw. It was plugged into a USB ext bay. I tried to scan with Easeus Data Recovery but all the files were shown renamed and no structure, so I give up on that. Hard disk were left unplugged since that time. I took out the 2TB drive to backup on the side, but when I plugged into the WIndows 8 system, the drive was shown as RAW, so either before in the WHS or when I start it up in the Windows 8 system, it turned into RAW. Please let me know your recommendation how I should proceed. Thanks!