Why is my drive so full on my Windows 2008 Server

My server is Windows 2008 R2 Standard Server.

I have a secondary SAS drive where all my website files are with the following properties:

1. NTFS File System
2. Allow files on this drive to have contents indexed in addition to file properties IS CHECKED
3. Simple Layout
4. Basic Type
5. Healthy (Page File, Primary Partition) Status

I have 3 folders on this drive:

Folder 1: 4GB

Folder 2: 2GB

Folder 3: 20GB

(These are the sizes of them when I click properties)

But the drive says it only has 10GB left out of 65GB. Why? I'm trying to make more room on this drive.

Solution 1:

Shadow Copies may be eating up your diskspace.

vssadmin list shadowstorage

Will tell you if it is.

Solution 2:

Or the recycle bin / system volume information could be consuming space (both hidden directories on the root of the file system).