Lost of Drive during image backup

Hi, I have dell i5 system. In which total hard disc is 500GBand only two partitions are made C+D, My problems started  when I tried to made image backup in Drive D, but after longtime i have no result found so I force log off my system. Later on when i re-booted my system, i shocked that my driver D has tottely lost and show 0 bight, please tell me how i recover my drive D which is now in hidden position. reply me as early as possible. Thanks