First, to regain your system sounds install the "Silent Switch Bypass" from the iClarified repository. To find instructions on adding this source to your Installer app follow this tutorial.
The bypass was created by XianLi and modifies your SystemSoundBehaviours plist.
Next, to regain your Ringtones all you have to do is install VideosTone. You can find instructions on how to do this here
Finally, for more discussion on this issue, check the Hackint0sh thread here