You did not say what software you used to partition your HDD. If you didn't use Partition Wizard, download and install it. It will let you to view your HDDs partitions and make changes, e.g., formating (NTFS, FAT32, etc., setting the partition Active, making a partition extended, logical, or primary. It is free and works with 32 and 64-bit OSes.
Really no need to use a program windows has it built right in . Right click on my computer and click manage. When that opens click storage and the disk management this will show you all your drives and partions then just click on the D partition and format it.