Hello friend, how are you? Goto ur BIOS setup and change the booting sequence to CD ROM ,floppy then HARD DISK. Also make a windows 98 bootable floppy. After changing the booting sequence, save changes to BIOS and insert bootable floppy and also insert the windows98 bootable CD into the master CD Drive and restart your system.
When system is booting from floppy, it will ask you "Start computer with CD ROM support". So select this option with thw help of arrow keys. Then press enter. Afetr a successfull startup of ur system, it will show the CD DRIVE letter at last. Note that letter and type "x:" and press enter.
Where x represent that drive letter in which you have inserted windows98 CD.
If it works then it means that problem is not with CD DRIVES but with windows.
So reinstall windows in that case.
Hoe this will solve your problem.
Take care of you and others and be happy.
Bye...
Dur-E-Wahab