WD external HD won't mount on desktop; changed itself to NTFS

[markgrant]

WD 2TB external hard drive. Have been using it on my MacBook Pro a long time.

Suddenly it doesn't appear on my desktop or in Finder. But it does appear in Disk Utility, although grayed out -- see attachment.

Then I noticed (in DU) that the format says "Windows NT File System (NTFS)" -- see attachment.

I did nothing. It has always worked fine on my Mac laptop. Did it just magically reformat itself to Windows format? Is there anything I can do?

Thank you.

Details:
2TB WD My Book external drive (the big fat silver ones from years ago)
-------
Mid 2010 MacBook Pro Intel
OSX 10.9.5

 

[sebseb]

I had a similar issue with my WD passport as well! I have been using it for 4 years now and It has 2 partitions, a NTFS and Mac OS extended. One day it was copying files and all of a sudden it ejected it self and then my mac would not read the drive at all. I left it connected to my laptop and after 10-15 min the mac recognized the drive again.

 

[TechpumpkinWD]

Hello there,
I see that the enclosure is properly connecting through the USB interface, but the HDD itself cannot be addressed. So the first thing to check is if the HDD appears to be spinning inside the enclosure? Sometimes if the drive is not getting enough power it could misbehave like this. Try connecting your My Book to a different wall socket, if you are using a power strip or battery backup, try plugging it directly to the wall socket. If you have any other available interfaces ( FireWire, Thunderbolt ) on the My Book try using them. Also try using a different USB port and a known good USB cable. Test the HDD on a different system if possible one that is running a different OS.
If that doesn't help think of what might have triggered the issue - have you made any changes to the system recently? Added new software or removed any? Do you have WD SmartWare installed? What model exactly is this My Book? Don't forget to update us with the outcome.