Can no longer see part of a logical drive in Win Explorer

Please forgive as this is difficult to explain. This was setup almost 3 years ago and so we are having a difficult time remembering how it was done or even what it is called, but here goes:

We setup a logical drive and within that drive was a "hidden "? partition. It was the only way we could come up with at the time to easily hide what was essentially a full partition in Windows 7. It has always been accessible in Windows Explorer if you knew where to look. All the data is still there and working fine when viewed through certain applications that have always accessed it directly, but we can no longer 'see' the data (folders) in Windows Explorer. It used to show up as a sub directory under the parent logical drive.

Any ideas how to directly access this again?

 

Have you tried showing hidden files?
http://windows.microsoft.com/en-nz/windows/show-hidden-files#show-hidden-files=windows-7
Neil.