Missing Driver File

I can't install drivers for my phone (they were installed before and
everything was working). The installer finishes, but Windows won't recognize
my phone in the Device Manager. I tried going to Control Panel > Phone and
Modem Option to manually install the phone as a modem, but any of the drivers
I choose ask me to point them to mdmzyxlg.inf, which is supposed to be in a
Windows Driver folder. It's not anywhere on my computer, so I tried doing a
repair install of Vista, but after I entered my product key and everything,
it said I had to exit setup and uninstall Nero 6 due to compatibility issues,
but I don't even have Nero 6 installed (I uninstalled it awhile ago and
installed Nero 7, which is supposed to be Vista compatible).
What should I do?