Hello, and Welcome to
DAL.
I'm assuming your D: drive is a CDROM?
If the above is true, first determine if it's hardware or software which is causing the problem. Boot with an EBD (Emergency Boot Disk) for WIN98. Choose "With CDROM support". Near the end of the boot process the system will tell you what device letter is being assigned to your CDROM.
When you get to the
A:\> prompt, insert a data (not music) CD (factory original, not a burnt/copied CD) into your drive, type in
dir x: (where x is the device letter assigned to the CDROM at the end of the boot). If you do get a directory listing, this indicates that the hardware is OK, and the problem lies within the O/S.
If you don't have an EBD, you can grab
this one from my webspace.
The above bootdisk image file is a self extracting file and has to be executed (run) from a running Windows machine in order to create the actual startup diskette on one of your floppy disks. (This image file produces the same bootdisk which 98SE creates.) This downloaded image file will format the floppy disk, write the files to the disk, then verify the file write, so it'll take a minute or three to create the bootdisk.
Ensure the floppy drive is set as the first boot device in the bios.
http://www.d-a-l.com/articles/library/23.html
NOTE: When you boot a machine with this boot floppy, it creates a RAMDRIVE in system memory to contain DOS system tools. Thus it will move your "normal" CDROM device/drive letter "up" one level. (If your CDROM is normally E: it will be F: when booting with this bootdisk.)
If the hardware is OK, the problem lies within the O/S. Try removing the drive through Device Manager, restarting, and letting the Hardware Wizard re-establish the hardware ID, drivers, resources, etc. If the Hardware Wizard doesn't start/find the drive on the restart, run Add New Hardware through Control Panel.
Post back with your results, clarifying what you have done.