how to recover info from WD Scorpio Hard DIsk?

hy Im a new at recovering info. I have Dell computer running wich has a WD Scorpio Hard Disk running windows 2000, It has 2 partitions C(OS) D(my files). One day out of the blue it wont let me access my files from the D partition nor run a scan disk. it gives me a “drive not formated, do you wish to format?” sort of message. Any wise words of advice will be really apreciated.

NG 😛