External drive recovery reference
Before you start
The external storage is more complex compared to a simple hard drive, because external storage involves additional components for data processing. When you recover data from the external storage it is desirable to get rid of this extra complexity and come down back to a simple hard drive(s). Because of this, most of the advice starts along the lines of "disassemble the device".
However, please keep in mind that disassembling a device most likely voids its warranty.
USB enclosure recovery
Disassemble the enclosure and get the drive out of it.
Either use another compatible enclosure, or attach the drive directly to the appropriate motherboard port in your PC.
See if this gets you the data back straight away. If it does not, this means the drive itself has failed, or the filesystem became damaged for some reason.
In this case, continue with a recovery as if there is no enclosure involved.
NAS recovery
If there is only one disk in a NAS, then get it out and attach the disk directly to a desktop PC. This may not provide immediately positive result. Most likely the filesystem used by the NAS cannot be read by Windows. Consider attaching the disk to a machine running Linux. This has a good chance to work provided the disk itself is not faulty.
In case there are several disks in a NAS unit, the recovery is more complex. Be prepared to encounter a RAID array, for which only vendor knows what the parameters are. In a lower-end hardware segment, a vendor would not typically tell you what they are, so you are mostly on your own. As far as a higher-end segment is concerned, you should have contacted your support representative already.
So, with a several disks in a NAS, you first need to determine if there are any mechanical problems with the drives themselves. To do it, attach the drives to the desktop PC and use whatever diagnostics software fits. Once the drives are determined good, your options are essentially down to
- Attach the drives to the Linux machine (guessing that the NAS unit runs some flavor of Linux) and see if you can somehow mount a volume. You'd better have a Linux guru try and do this for you.
- Attach the drives to the desktop PC and try to get a RAID reconstruction software to work with it. If successful, you can then copy the contents of the broken NAS directly to the PC.
- Give it up and send the NAS unit plus disks to a data recovery lab for an analysis