Put simply, if the components in the drive are still working, there’s a chance you will recover the data yourself. If there’s mechanical damage, a data recovery professional is the only answer. So before attempting anything, it’s worth diagnosing the problem.

Indeed, it might not even be a hard drive failure, but a plethora of other glitches that cause boot failure. So, it’s worth hooking up the failed drive to another computer, ideally through a USB drive adapter. On a Mac, simply hook your non-working Mac to a working one using a FireWire cable. Hold down the T key to ‘target boot’ as you power it on and see if the files are revealed.

If your files don’t show up then you need to think about data recovery. All recoveries fall into two basic categories – logical and mechanical. If it’s a logical failure, then there is a chance the data can be recovered without intervention from a data recovery professional. If the data hasn’t been overwritten, chances are it’s just that the drive is not able to find and navigate its own data.

Almost all logical failures can be recovered without the need to open the drive. Typically, when you start the hard drive the computer’s BIOS will locate the device. The electronics and mechanics are functioning but the media is defective. However, if you misdiagnose a logical failure and attempt a recovery, chances are that you will cause irreparable damage to the platters, rendering the hard drive completely unrecoverable. So, if the drive is not recognised by the BIOS, it’s extreme logical failure or mechanical – best left to the professionals.

Now we’ve established that the drive is recognised by the BIOS we need to find software that can recover the data. There are essentially two things to consider here. Firstly, don’t be sucked into generic data recovery software. Think about the file types you are trying to recover and buy the appropriate data recovery software. A repair to an SQL database is very different to a partition recovery. Stellar Data Recovery is a good place to start. They offer tools for every eventuality and have free downloads for Windows and Mac.

Secondly, if your data is important clone or image the drive first. High end data recovery utilities will have a facility to take a raw ‘image’ and copy this to another hard drive. You can then scan and recover the ‘image’. If your critical files are not recovered, the original media remains unaltered and you can attempt another recovery. Once you start altering the state of the original media, further attempts at data recovery become much more difficult!