To restore or add ring-tones and other audio to an Android phone either post or pre-root.
First download audio-resources.zip from here :
http://www.cyanogenmod.com/downloads/audio-resources/Create a folder called 'Media' in the root of the SD card if it doesn't exist and then a folder called 'Audio' inside that folder and extract the four folders in the zip into that folder.

Once copied, the phone may take a while to acknowledge their existence, if they don't show up in your settings options, leave the settings menu and wait for a couple of minutes and retry.
The G1 is a little slow in scanning new audio but it gets there eventually.
The only problem with the above procedure is the ring-tones and notifications won't be accessible when the SD card is mounted for computer access, if this is a problem to you then you'll need to download the SDK and use the following procedure under 'internal memory install'
http://wiki.cyanogenmod.com/index.php/How_to_install_more_audio_ringtones_and_alerts