There is nothing wrong with your label names but moving
your programs to drive D: is not recommended. Many programs
will unfortunately not recognise the change, which means that you
will have the folder "\Program Files" both on drive C: and on
drive D:. Much better to make drive C: 20 GBytes in size and
reserve it for Windows and for your programs. You should
then keep your data on drive D:.
Click Start / Run / diskmgmt.msc to find out what's happened
to your missing partition.