Hello, I want to change the name of my directories(C:& D but I dont know how to do it.
You say one thing you want to do, but describe another.
You cannot change the drive letter Windows is operating with. There are hundreds of registry entries that rely on the drive letter staying what it is. Windows itself will not allow you to change it's drive letter for that reason.
You can change the drive letter of a data storage disk... but one must wonder why do it at all?
You can change the name of some folders in either drive by opening Windows Explorer, right-click the folder and select "Rename" but this is somewhat hazardous if you change the name of a folder that has registered links to files in that named folder (such as, "Program Files," you would be shooting yourself in the foot to rename this one).
Maybe you want to really do something that wasn't communicated in your question. Please review what you desire to do and enlighten us a bit more.