c:changed to D:after clone-how to chng?

I've cloned my HDD using Easy Migrate 3-4 times- no problem. Wanted to update & upgrade system, had problems getting it to work. Finally did, but I must have overlooked something, as both the original drive & the HDD I cloned to now come up as D:. They finally ran after I ran the re-install (repair) from the CD, chose install to c:windows, but it still stays D:. Naturally, many apps (USB scanner & printer, Norton, etc) don't work, nor can I uninstall & reinstall! Is there a DOS prompt command I can use to change back to c:?? Thanks,
Ralph Mason