Every computer user should understand that hard drive failure is a very real possibility. Just like any other piece of equipment, computers are mechanical and will fail and will need to be repaired or replaced. Some components, such as monitors, keyboards, optical drives, do not present much of a challenge and can be replaced easily on most computers, especially desktops. Even the motherboard, memory cards, network cards, and similar components do not present a major problem. When any of these components fail you haven't really lost anything; you just need to replace them.
But when a HDD fails, you have quite a different situation. Not only do you have a physical component broken, but you also face the loss of irreplaceable data. You can just pop in a new CD Rom drive or memory card; replacing your data could mean recreating it, word for word, unless the data can somehow be recovered. Fortunately, many times the data can be recovered from a failed drive. How effectively and completely the recovery is depends on the failure type.
Physical failures are caused by drive component failure, including read/write head damage caused by wear or abuse, and electronic component failure, caused by voltage spikes or overheating. Logic failures are caused by damaged or altered file structures and can be the result of virus infection, program failure, or improper registry changes. Logic failures are often easier to recover since all the data is still there, it just can't be read.

Retrieving data from external hard drive is not as difficult as many people thought. Read the tutorial below to see how to recover data from external HDD.

First of all, stop using the external hard drive immediately.

When data is lost, the space used to store data are normally not erased, the system will mark the space as free to use. If new data are written onto the external hard drive, the new data may overwrite the space of lost data, which will make them unrecoverable.

After scan compeleted, ou can see a list of recoverable files. You can select files you want to recover, and then press Recover button to start recovering the files.

There are some external hard drive data recovery software available for your choices. You can search it on the internet to get another one. But whenever you choose a data recovery tool, download it firstly and scan your external hard drive to preview whether it can do as it claims. One more tips, if your hard drive was badly physical damaged and it can't be recognized by your PC any more, then it is probably dead. And your data can't be recovered by any software.