There are two main methods of recovering data from failed hard drives.
First of all, you can run specialized data recovery software that could retrieve all of your important data files. In the majority of cases, you will be able to recover the data from your failed hard drives without too much trouble using data recovery freeware, or purchase fully supported software if you prefer.
Please note hat data recovery is not always possible if the actual problem is due to aging or faulty hard drive component such as a broken head arm. In those extra-ordinary cases you would have the hardware fixed by an expert technician before being able to access any of the precious data on the hard drive.
Additionally, there are no limitations to the different types of operating systems which you may be trying to recover data from, such as Microsoft Windows to Linux systems. This also extends to include different file formats such as FAT32 and NTFS which are very common file formats for Windows systems, or the Mac OS file system used by Apple Macs.
In the case of a RAID volume failing you would have little alternative but to send your hard drives to a data recovery expert to restore the RAID configuration as well as the data. This would also be the case if your disk partition failed and you were unable to access the data held on that particular partition or disk.
The recovery of your important data and files from failed hard drives is possible using data recovery software. If your hard drives are badly damaged, or the RAID volume-set has failed and the data on the hard disks is inaccessible, requesting professional assistance from data recovery experts would be a better option.