It may be dead.
I refurbished an ex-council office PC for grandaughter's use. The PC was about 4 years old and the CDROM had had little or no use, but it was dead.
One possible check if you have a 98 setup floppy is to boot from it as far as the A:> prompt and see if you can "find" Drive D: or whatever it is called. Better still, stick a CD in the drive and see if you can see its contents.
If you can "see" it in DOS then I am wrong and the problem lies with Windows - Worth another post!