How to make a hidden partition visible

Solution 1:

• Right-Click "Computer", Click on "Manage" (you need Admin rights for that!) and select "Disk Management" in the right area of the upcomming window.

• Right-Click your hidden partition and click "Change Drive Letter and Paths..."

  

• Click "Add...", select a drive letter and click "OK" in both of the small windows.

  

A primary partition is the a partition on a harddrive. You can create up to four primary partitions. When you want to create more then four partitions, you have to create 3 primary partitions and one extended, which is a workaround to create more partitions. All further partitions created in the extended partitions are called logical drives. Booting is only possible from a primary partition.
See also: http://windows.microsoft.com/en-us/windows-vista/What-are-partitions-and-logical-drives

Edit: Seems like Windows only allows 3 primary partitions. Might be so to prevent users from creating 4 primary partitions so they don't have to delete one partition to create an extended one. Windows 7 only allows the fourth partition to be an extended partition.

Solution 2:

When you have some partitions hidden to your system, that's because they have the flag "hidden" applied to them.

I use a free application to manipulate all available flags and other disk operations:

MiniTool Partition Wizard Home Edition 7.5

1. On the list, right click the desirable partition;
2. Access "Modify";
3. Click over "Unhide Partition";
4. On the far left of your toolbar, press "Apply" to save the settings to the disk;

^{When finished, you may need to restart the PC to have windows presenting the new partition.}