In Australia, there are a lot of companies out in the computer repair marketplace offering Data Recovery services for damaged hard drives, solid state drives, raid systems and flash drives.
Most of these recovery services are using a software package for $69.00 with a promise of all data recovered from every situation, well, that just is not the case and in most cases will make the data even harder to retrieve.
When a hard drive has certain types of physical damage like:
Degraded read / write heads
Damage to the platter or disc
These errors will cause the drive to slow down and testing the smart of the drive will show bad sectors on the drive.
This is when the drive should be shutdown and taken to a professional data recovery lab or passed on to someone with the knowledge and tools to deal with the problem correctly.
Software is good for recovering deleted files or when formatting discs but that is where this ends and efforts to recover a faulty drive using a software is only going to cause further issues.
If your drive suddenly stops functioning or slows down then there has to be something physically wrong with the drive, this will be noticed by performance of your computer or laptop as it will slowly get slower at doing simple things like starting up the device.
Software tools send a standard read command to the drive and expect a response within a certain time, if not then it will continue sending the commands until it eventually gives up. This is bad news for the drive as it tends to damage the drive even further.
You can checks the file system and file system metadata of a volume for logical and physical errors. Simply run CMD using chkdsk command to gain further insights about the drive on Windows.
When a drive gets a read command the following will happen:
The sectors are read by the read / write heads
This is loaded in to the drives cache
The checksum of the user data is checked by the CPU
This checksum is then compared with the original checksum to ensure it is correct
If these match then the data is correct and is sent via ATA channel
IF THERE IS a MISMATCH THEN THE HEADS WILL TRY ANOTHER READ AND WILL DO THIS MULTIPLE TIMES
If the drive detects a bad read then this will be written to the service area of the drive
The service area is on the platter and is a set of logs recording things like bad sectors in the smart of the drive
If the heads of the drive have an issue, then this will cause further damage
So the correct thing to do when recovering data is to use the correct hardware to first analyze the drive for errors, and identify a course of action to recover as much data as possible (ideally all data). This cannot be done for $69.00 we can only wish.
The last thing you want to be doing is connecting your drive to a computer running an operating system, because the first thing that will happen is that the operating system will try to mount the drive, and this alone is enough to stress a failing drive even further.
Data recovery and repair must be carried out at the lowest possible level to protect the drive, if at all possible, the drive must be repaired before a low level image is made with a data imager.