for whatever reason this has happened, the reason the devices (network, internet, etc) do not work correctly is because the drivers were not install on the OS that ended up being installed. It may be that the OS you wanted to repair is still there, maybe not. Make a Linux Live CD and boot to that. You might want to look at this to save any data before continuing on the path that has been entered. http://www.howtogeek.com/howto/windows-vista/use-ubuntu-live-cd-to-backup-files-from-your-dead-windows-computer/
Disregard the Vista part as this works with any Windows OS. If the OS install that has all the programs etc is still there, come back with details that the investigation has revealed. Save any data that is found before continuing.