I am a data recovery specialist and I do hard drive recovery. I also teach classes and have written 10 books on this subject. I can tell you from first-hand experiences this isn't an easy job and what they should you on YouTube can destroy all the chances you have of recovering your data for good. A hard drive can faile for a multitude of reason. Today the new technology in hard drives is very sophisticated which makes it even harder to recover the data on these drives. In the first models of hard drives, the drive would have one or two heads. In these cases, it was easier to change out a head stack to recover the date on the drive. When a head dies the hard drive makes a clicking noise. You will need a clean room to sway out the head stack so that no dust or dirt gets inside the drive. Furthermore, when a head crashes this can leave tiny scratches on the surface of the disk that can't be seen with your eye. You'll need special tools to examine the disk surface. You will also need the special tools to use to remove the heads and swap them out. Other problems in a hard disk can result in corruptions in the SA or system area of the disk. This area is only accessed by special tools that can read the mods in the disk and determine which one is bad. You'll need to overwrite these mods with donor mods in order to get the disk to recognize again. You can also have issues with a ROM being corrupted on the PCB. This will take a special took to write the ROM back to the PCB so it can read the SA again and start the disk. If you have a disk failure and it isn't as simple as a corruption in the master file it is best to seek professional help before you lose your data completely.