Strange clicking sounds coming from your hard drive are normally indicative of a head crash. These noises are caused when the read/write head in the drive reaches the edge of the platter, and data recovery is typically successful as long as the platters are not scratched.

Grinding and screeching sounds indicate that parts of the hardware – such as the motor or spindle – are failing. Although this results in a time-consuming data recovery process, there is a high chance of saving your precious data with professional data recovery techniques.

While it is difficult to define the cause of your drive not being recognised, it could be due to anything from an issue with power reaching the drive to a blown component on the PCB board to a serious head crash. Make sure your SATA cable is  tightly connected, as they can sometimes come loose. 

The firmware is like the operating system of the hard drive, and without it, the drive wouldn’t even spin. As such, firmware failures can be devastating. Typically, we can simply re-flash the firmware, although we may need to rebuild it from the source code if this fails.

If the hard drive is recognised by your machine, but you’re unable to perform any read/write tasks, it's likely the file structure is corrupted. In this scenario, the chances of a full data recovery are high, as long as the data hasn’t been overwritten.