Hey there, StanCz!
Could you provide us with more details about your external HDD model? The WD N600 My Net is the router itself.
I'm sorry to hear about your data concerns, though.
🙁 I'd follow @Emerald's advice and put the HDD back in the external enclosure. We have some external hard drive models that incorporate a hardware encryption, which will make your data inaccessible without the original case.
I'd also suggest you to test the HDD while plugged into your Windows computer using
WD's Data LifeGuard Diagnostics. Running the QUICK and EXTENDED tests will help us determine the health and SMART status of your WD drive.
If you haven't done this already, you might also want to try another PC/laptop and use a different...