Samsung is pushing a new update to Galaxy S4 (I9500) in India. This is not another Lollipop update to bring the device to latest Android Lollipop version. But this new update will fix the missing Mute option from the phone menu.
Earlier, after Samsung Galaxy S4 received the Android Lollipop update, it introduced a lot of problems. In the latest update which comes with build number LRXX22C19500XXUH0C1, fixes many bugs introduced earlier. The build itself is pretty new which was backed on 3rd March.
The update is 327 MB and it is unknown at this moment what are the other improvements added to this. But one noticeable change is that Samsung KNOX is now upgraded from version 1.0 to 2.0.
This is an OTA update, so you must get an update notification. If you have not received the notification till now, you can always check by Going to Settings >> About Device >> Software Update >> Update Now.