Control panel/administrative tools/computer management/disk management
Can you see it in there (with no letter assigned or with some other letter)? If yes right click on it and click assign new drive letter and paths and let it assign some new free letter. Make sure you don't select to format it.
Actually I did all these steps, I can see only C: drive, d drive is just showing but its not represented by any letter D: I tried already what you mentioned, its giving message that need to update disk management console, even I try to make system restore, nothing workout. By the way thank you for your support.