I cant use my CD-ROM

I own a etower 433i,and I have windows98 second edition. I am unable to use my CD-ROM,everytime I put a disk in it I get a message that says: drive D:is unaccessable,wrong media,or it says: the volume is not set. Its driving me crazy CAN SOMEONE PLEASE HELPPPPPPPPPP???
Thank you,
Stacy