You can recover data from a failed hard drive whose components are still functioning by using a USB universal drive adapter to hook it up to another computer as a secondary device. If that computer is unable to access the hard drive, you can use data recovery software to transfer the data to the working hard drive. A mechanical hard drive failure may require the use of a professional data recovery service.
There are numerous glitches that can cause a hard drive to stop booting up properly, but as long as the mechanical components are not damaged or dead, it is possible to recover the data without hiring a professional. A mechanical failure often causes the hard drive to make a clicking sound due to broken parts. If the failure is due to accidental formatting or a corrupt file system, the drive is simply unable to read its own data. Using a second computer allows you to access the data and move it to a properly functioning hard drive.
If accessing the data requires the use of data recovery software, you can typically find free diagnostic demos that tell you what the software is able to recover before you purchase it. However, with this type of recovery, the process may take days to complete and requires you to sift through and reorganize the recovered files. Additionally, this type of software does not work with mechanical hard drive failures.