3COM CNC3ACx556 LAN modem not working

I have a Latitude c600 with a 3COM CNC3ACx556 LAN modem not working.  I may have inadvertently unistalled some software on my computer because it was working up until Sunday.  I have Win 98SE and I have earthlink DSL that I access through my ethernet connection.  When I try to log on now, I get a error message that says "unable to find connectiod".  I have installed the latest Bios and tried reinstalling the modem but my modem does not get recognized automatically and doesn't appear in the list.  HELP.