In the sound devices, right click and tick "show disconnected devices" Then you should have a disconnected realtek which is likely to be the rear output. If you plug in something into the green jack on the rear IO, it should become connected, so you can select it and set it as default. I might be completely wrong though, I haven't used an integrated card in years.
Also, if I were you, I'd uninstall the sound card drivers, as it should work fine without them. They just slow your PC down, and can potentially cause problems like this.