Vista installed drive but cant assign drive letter

I have a 1T My Book essential External hard drive with data on it. My computer (Vista) installs it and everything is ready to use and working correctly. The drive is not under computer but it is under disk management. It has three partitions on it and when i right click to assign a drive letter its greyed out. The only option i have is delete volume and help function.

Where my c and d drive has NTFS under file system the ehd has nothing under file system.

The partition info is as follows:

partition 1 200MB Healthy (EFI System Partition)

partition 2 931GB Healthy (Primary Partition)

Partition 3 128MB Unallocated

I cannot format the drive as i need the data and i have no idea how to get access to this drive.

If anyone can help let me know, Thanks

Sounds like a issue with the drive to better assist you is it possible to post a screen shot? It would be greatly appreciated.

Right-Click at the left side of the “Disk Management” window, where it says “Drive 2” (or whatever) and make sure the drive’s “Online”

here is a screenshot of the disk management


If there’s an EFI partition (and if it’s not reported as NTFS), I have to assume the drive is Mac-formatted.

Windows can’t natively access HFS+ drives.

You’d have to download drivers to allow Windows to access the drive.