If your trying to format, and reinstall win98 you need a win98 bootdisk.
If her machine is still working you can create a boot floppy by going to
add/remove programs, there will be a tab to select and follow the
prompts, if my memory is correct, its been awhile. Or you may try
going to
www.bootdisk.com they used to provide the info needed to create
a boot cd.
You will have to set bios to boot from floppy first, then hdd. Once in
you will have to type in c:\format, then away you go. If you make it
that far and are confused post back here..You know that microsoft
doesnt give support for 98 anymore..