What's your exact problem? You're not very clear about drives and partitions. What I understand:
- you've got 4 partitions of each 20Gb
- 3 of them are totally empty
- the properties of the fourth partition (say, f:) show it has 1 Gb data and 19 Gb free after you formatted it (say, format f:)

That's the right picture? Or do I misunderstand it?
Is it an external hard drive or an internal one?
What does Disk Management say about the drive?
What does dir f: (if it's f:) say about files and folders and used and free space on it?
Did you already try chkdsk f: again to see what it does and reports?

Kees


Kees