External Disk no longer readable - how can I fixe it?

[Internationalus]

I purchased less than one week ago a 1TB Buffalo External Hard Drive model HD-PA1-OTU3-AP MiniStation Thurderbolt. I had formatted for use on Mac and PCs. I then downloaded some 500 GB of data on the disk.

I used it on my MAC (13 inch Mac Retina, operating on OSX 10.8.3 ) and it worked just fine for the first few times. I tried to use on my desktop PC but it failed to recognize the disk.

The same day in the evening I used it once to see a movie on my Mac (which was wonderful). When I finished I ejected the disk by dragging it in the trash.

The next day when I tried to use it again on the Mac I received the following message:

The disk you inserted was not readable by this computer.
Initialize Ignore Eject

When I pressed initialize and then the verify option, I received the following messages:

Verifying partition map for “ST1000LM024 HN-M101MBB Media”
Checking prerequisites
Checking the partition list
Problems were found with the partition map which might prevent booting
Error: Partition map check failed because no slices were found.

Any ideas what happened to my drive and how I can fixe it and not loose the data on the disk??

Thanks for you advice!

 

[josephmccutchen]

I purchased less than one week ago a 1TB Buffalo External Hard Drive model HD-PA1-OTU3-AP MiniStation Thurderbolt. I had formatted for use on Mac and PCs. I then downloaded some 500 GB of data on the disk.

I used it on my MAC (13 inch Mac Retina, operating on OSX 10.8.3 ) and it worked just fine for the first few times. I tried to use on my desktop PC but it failed to recognize the disk.

The same day in the evening I used it once to see a movie on my Mac (which was wonderful). When I finished I ejected the disk by dragging it in the trash.

The next day when I tried to use it again on the Mac I received the following message:

The disk you inserted was not readable by this computer.
Initialize Ignore Eject

When I pressed initialize and then the verify option, I received the following messages:

Verifying partition map for “ST1000LM024 HN-M101MBB Media”
Checking prerequisites
Checking the partition list
Problems were found with the partition map which might prevent booting
Error: Partition map check failed because no slices were found.

Any ideas what happened to my drive and how I can fixe it and not loose the data on the disk??

Thanks for you advice!

You tried doing Verify, good, but did you try doing Repair also?

Do you have the 500GB of data on another source (internal/external drive, another computer, etc)?

You said you formatted the drive for Mac and Windows; how did you format it?