Each week we receive the same common search request on how to recover an external hard drive. To be direct with this response, the answer is in two halves: there are some things you can check (and do) without risk, but after those items you should not continue as every further attempt will cost you data. This guide gives you both, in order.
First: use one good cable with your external device connected to an open port on your computer (do not use a hub or a keyboard passthrough). Try swapping cables, but better still try using one you know works, and give it thirty seconds. A surprising share of "dead" externals are just a £5 cable or a starved USB port, and this check cannot hurt anything.
Second: listen and look. Does the light come on? Can you feel the disk spin up? Is there clicking, beeping or grinding coming from your hard drive? Don't act on it yet; take a moment before proceeding to make a mental note of everything you have noticed so far, because it decides everything below.
Third: check Disk Management (right click Start→Disk Management) or Disk Utility on a Mac: look, but don’t touch. Decline if Windows wants you to initialise or format the disk. Once initialised, a brand new blank map will be written onto the exact areas needed by any data recovery operation. It’s good to see your drive identified as either RAW or unallocated; fixing it at this point converts a recoverable job into a hard one.
Any mechanical noise (clicking, beeping, grinding) will stop your DIY recovery route immediately. Mechanical noises include: heads hitting; motors straining against stuck heads; or the platter being touched by an object that should never have touched it. Unplug it from the wall and do not plug it back into your computer to "check". Nothing in the world can repair mechanical problems with software, and each powered minute will cause additional physical damage.
If there is no noise coming from the device (no spinning, no light), it is most likely a power or electronic issue (the enclosure's USB bridge or the internal circuit board for the drive). In many cases these can be repaired at the component level. Do not remove the hard drive from the external enclosure as many of the enclosures actually encrypt through the enclosure itself; therefore, once removed from the casing, the raw disk is unreadable.
If the drive is spinning normally but invisible, or visible but RAW, then these are both typical patterns associated with either firmware or file system corruption: the MiniStation pattern and the Elements pattern in our case files. Almost always, the data is still intact, but it cannot be accessed by anything running on your computer.
The main duty of recovery software is to recover deleted files from a working disk (drive). A functioning disk with lost data is the perfect use case. Run reputable recovery software on that drive; then recover the data to a different drive. Then you're done.
Software that is intended to recover data will be the most costly tool you can run on any drive that has any symptoms as described previously. Running a scan will cause the software to read every single sector for an extended period of time (in many cases this will be hours) which is exactly what a failing hard disk cannot handle. This has led us to identify numerous failed drives, that were just in need of a routine job (£300), but due to running such a time consuming scanning operation, they are now unrecoverable. The software didn't find your files; it finished your drive.
It really is very simple: the only way you can use software on a hard drive is when the drive itself is completely stable. If you deleted files on an otherwise good disk, fine. However, if you want to perform anything else, the first step has to be to stabilise the drive, which means doing work at the bench.
This isn't about having better or smarter software: it is simply about running under the operating system. Hardware-based imaging systems communicate with the drive as if they are part of the hardware. They issue requests for data, using timeout values for each sector that are set much lower than those used by normal operating system based file recovery tools. This allows a malfunctioning section of the disk to receive one gentle request for information rather than receiving a rapid fire series of requests, which could cause further damage to the disk. When a firmware-based error occurs, these errors are typically fixed in the drive's service area. No consumer-level tool has access to this area. We repair mechanical issues using donor components, installing them specifically to allow us to take a single, careful read of the damaged area.
All repairs, rebuilds and experiments are performed against a copy of the original disk. The first thing we do with every external arriving device is create a sector-by-sector image of the disk. And from that point forward, all repairs, rebuilds and experiments are done against that image while your original remains powered down. That's the one option that home users don't have available to them: being able to fail without consequences.
In addition to being honest, the economics of this service are also very fair. The diagnostic is complimentary (free), and external devices are charged in the fixed £300 + VAT single-drive band. In most cases, you won't be asked for payment unless your data has been recovered. Once you receive a quotation, send it in to us from wherever you may be or drop it off with us at Tay House on Bath Street.
At some point you'll know whether the cable, port and a careful look will get your data back. If they don't then stop there as you've done all you can without risking anything. The complimentary diagnostic service will tell you exactly which part failed and will put a fixed cost of recovery (£300 + VAT) into writing prior to commencing any work.