don’t understand dos

I am trying to reinstall windows 98 on a friend’s computer that crashed. I can’t get dos to reconize the cd rom. For some reason dos won’t work on any commands except dir. I have several drivers including cdgod55 but when I type install.exe at either the a or c promt all I get is bad command. I even bought a new drive with a driver that will boot in dos but that won’t work either.Please help this is driving me crazy. Thanks Dawn.