Hi There
I have tried everything and searched many websites but can't find an answer to my question.
I have a external Hard Drive, that I have successfully used every day, I took it home and had to format it and then put new info on it. When I brought it back to work, it would not automatically pick up the drive.
So I went into computer management, and the drive is recognised there, but has no volume assigned.
It won't let me assign a volume, as the options are all greyed out.

It's almost like it is recognised (reads Healthy, Active, Primary Partition) but just won't come up on my computer so I can access the files.

I have done shut downs and reboots, tried different USB's and tested it on other computers (my home computer which is a mac), works fine.
This computer is a Vista. However worked perfectly before I took it home and reformatted it emptied the contents and put new info on it.

Anyone out there - can you help?

Most likely is that when you formatted it on the Mac, you used the default (Mac-only) HFS+ format. This won't be accessible on Windows PCs.

Here is a good article on how to format the disk to make it usable on both the Mac and PC.

I hope this helps clear things up,
WallyH