Welcome to the TH Community, @RaRelis!
Can you please provide more details about the troubleshooting you have done so far? I'd suggest you check how the external drive is detected if plugged in another USB port on your computer and also try using a different USB cable. If you have access to another PC/laptop, try connecting the HDD there as well and see how it will get recognized by the other system.
I'd also suggest you go to
Disk Management and see if the drive is recognized there. Posting a screenshot from there would be really helpful to us?
What is your OS version? Have you had any recent updates?
As soon as you can access the data on the external drive, make sure you back it up (copy it) somewhere else as well. This is the surest way to avoid any potential data loss.
Good luck & keep us posted!
SuperSoph_WD