in it's present state, on either platform.
Data Recovery software may be able to bring back the data though.
I would suggest that you download a few of the "free trial" ones and see which one finds the most data before you purchase it.
One of the prime things when working with a third party, your sister, in this case, is to ask as many questions as you can as to what was happening before the problem started to happen.
Perhaps she would have told you that she had no trouble seeing the hard drive when it was plugged into her Mac. Terminology is also important here. Cannot see it when its connected to a Mac is completely different to Cannot see it when its connected to a PC. On the Mac, the drive will mount on the desktop which means the user can "see" it. As you know, drives don't mount on the desktop in Windows, so the user cannot "see" it.
Water under the bridge now.
Try the recovery route and be prepared to be struck off the Christmas card list.
This is entirely my fault - I am a PC...ugh...
I "Initialized" a Mac external hard-drive in a Windows 7 environment (placed an MBR on it) - but DID NOT format the drive - I stopped before it got to that point.
My sister has an external hard-drive she has been happily using with her Mac. She called me, and said "I can't see it when I plug it into my laptop (running Windows 7).
I know a fair amount about PC hardware, and did some troubleshooting with her - including removing the USB drivers, letting them reinstall, etc...but no dice...
Then saw a forum about using Disk Management - so we could see the disk in there, and it was asking to Initialize the disk before it could be used - and we did so...but again, stopped short of Formatting it.
Now, when the USB drive is plugged into the PC laptop, the drive letter shows up - but asks to format it before using...
It's at that point when I found out she has never used it on a PC (and when I learned something new, duh - that an external drive formatted for a Mac is exclusively for a Mac unless some other special software is used...) - oooops...it's obvious now.
OK - so - I had her try to plug it back into the Mac, and now she gets a message that the disk cannot be read, Ignore, Initialize, or Eject.
What I want to be able to do - is have her get the data back from that external HD (via the Mac) - could someone be kind enough to point me in the right direction on how to do that safely? Thanks!!!!!
(Yes, I take the blame on this one - it was all my doing...greatly appreciate the help!)