lost drive letter d: after restore

I tried to restore my corrupted c: drive with disasterous reults: I was able to recover the mbr and the correct c: designator for the main NTFS (active/boot) partition, but the second (fat16)partiton nolonger has a drive letter (... instead of d:) also that drive letter is now one of the cdrom drives. How do I get this drive letter back