It just sounds like he didn't sys the drive when he formated
When at the a: prompt you would type so it looks like:
A:\>format c: /s --------the /s switch copies the system files making the drive bootable
Then you'll be able to get to the c: prompt. There can be reasons to sys the drive. It's not really necessary to sys when formating, installing windows also installs the system files making the drive bootable.
The win98 bootdisk has cd drive support.

Vera