Was it powered when it was dropped?
As it's still recognized as a storage device but not as a drive, it sounds like the hard drive has sustained damage and the housing is still OK; if this is the case you probably need to find a professional data recovery specialist (with a clean room).
If you are associated with a University, try contacting the IT department, they may have a recommended data recovery firm.
yes, It as powered when it was dropped. Our institute does not have any link to data recovery firm.
Another issue is my drive is still in worrenty period so I want to recover data without opening drive. Option of proffesional expert is open but before that I want to try on my own with some software or other external trick. Is it possible?