I suddenly saw that a system partition became shown, although it was along with another HP tools partition hidden as it is shown in this screenshot below:
Also, I have post the screenshot of my entire disk::
The HP tool partition is only still now hidden
I clikced on the folder options, then I chose the 'view' tab, after I checked the three options above.
The option 'show hidden files and folders' was checked before system partition have becom shown under my computer. So I think this option doesn't do anything with showing or hidding partitions.
How can I let it be hidden again.