Whatever the type of computer:
Unplug the device and do not try anything yourself.
Do not attempt to recover the data with software you do not fully control, or with methods found online: you would make things worse. And do not follow instructions from an AI (ChatGPT, Claude or any other): it can neither see nor hear your device.
An external hard drive is especially exposed to knocks, drops and unplugging at the wrong moment, on top of the normal wear of its mechanical parts.
A failure can show up as an unusual noise, a drive the computer no longer recognises, a prompt to format, or unusually slow file transfers.
OaOa Informatique has recovered hundreds of external hard drives that were damaged, corrupted or accidentally erased, whatever the operating system involved (Mac, Windows, Linux). Our success rate reaches 95% when the device has not been tampered with after the failure.

Frequently asked questions
Not always: a drive formatted as APFS or HFS+ by macOS is not recognised natively by Windows, and an NTFS drive cannot be written to directly from a Mac. A drive your computer no longer recognises is therefore not necessarily faulty. However, if a message asks you to format it, do not do so and call us.
In 90% of cases it is the drive itself, with a variety of faults, rather than the enclosure or the cable.
Do not touch it any further, and bring it to us for a diagnosis.
Yes, it can be, but the password is usually essential. Even when the raw data is extracted from the drive, it stays encrypted, and therefore unusable, without the key or password that decrypts it.
So bring the drive's password, and the original electronic enclosure if you still have it: some models use an encryption chip built into the enclosure.
It can be minor and simply come from the power supply unit. Stay careful: a faulty power supply can also have caused a surge and damaged the drive's electronics.
Do not test with whatever power supply comes to hand. The voltage, the polarity and the electrical specifications must be checked before any replacement.