PGP Deleted D Drive after Whole Disk Decryption

My 300 Gb Hard drive is partitioned into C and D drive. Each partition is 150 Gb. The disk is Whole Disk Encrypted and both drives have been accessible over the past year. After Whole Disk Decryption, D Drive no longer exists. If you navigate to Windows 7 Disk Manager you see that the entire 300 Gb is declared as C Drive. This is the strange part. If you open up windows explorer and right click on C drive and select properties, it still indicateds150 Gb. This tells me that D Drive is still there. Does anyone know how I can recover D Drive.

Thank You