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 the following steps:
Press the Installer icon on your Springboard to launch it.
Press to select the Sources tab at the bottom of the screen.
Press the Edit button at the top right of the screen.
Press the Add button at the top left of the screen.
Set the source url to http://installer.iClarified.com then press the large OK button.
Press the Done button at the top right of the screen.
Press the Install tab at the bottom of the screen.
Press to select iClarified from the list of Categories.
You can now select the desired package for Installation! Which would be "Silent Switch Bypass".
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.