not sure about the file name but in 98 try start search and look for a file called ( format.com ) write this to a floppy disc
Then reboot with your windows boot disc in the A drive at the "a" prompt remove the boot floppy and replace with the floppy with format.com on
Then just type format c:
If the boot disc leaves you in any other drive than A type a:\ to get back there then format c: with the new floppy in the drive
It sounds like the boot disc you have does not have the format function on it