In Start Menu, my Pictures & Music folders can't be opened

Hi, this is the story

Since I don't have enough storage in the C drive, I designated my Documents
folder (the sub-folders which were Pictures, Music, Videos and so forth) into
the D drive

So in the D drive, you can see all my Documents folder and the sub-folders
with the correct icon.

However, the time has passed by, and I guess something went wrong.

Because when I try to open my Pictures and Music folders into the desktop, I
cannot open. And if I try to right-click it I only see Copy, Change Name, and
Properties. So if I click properties everything is empty, therefore I cannot
bring my D drive's Pictures or anything at all.

The problem arises when I try to install Itunes or Adobe Acrobat reader.
Because I guess they have to do it with some sort of original Documents
folder, which makes the installation unsuccessful, saying that "Documents is
not a valid folder or route" (my Windows is Korean so I don't know what the
English will say)

So basically my question is, how can I recover the regular route and make
the Documents folder and the sub-folders into the original C route? This is
really frustrating and I don't want to re-install Vista again because I'm
really settled now with the programs installed and everything.

Please help me!!!