One of my physical hard drive disappear!

I work with Windows XP home and have 3 physicals drives, C: D: and E: . This setup has been working fine for over a year. Lately, I connected on FTP server with someone I don’t know. Since then, My D: drive is no more readable in XP. It say that thefile system is RAW, that I have to format the drive. By booting with an old win98 disquette, DOS sees all the info as a FAT32 file system with all the file ( 35 Gig ). The problem is that it is hard to backup since it is in the aaaaaaaa.bbb format. Is there any easy way to get back the drive as it was before ?