iPhone 3GS came up with a unique irritating problem after iOS 5.0.1 update. All of sudden you will lose the sound out of your speaker, which means you wont be able to hear Music, Ringtones, Key Sound, Lock & unlock sounds etc. Interestingly you will be able to hear all these sound’s if you attach your headphone to device. You would be able to hear music via HeadPhone & able to receive call etc but sound will not come through speaker in the bottom.
To fix this Problem i have tried few tricks that might also work for you .
1. Clean you iPhone Headphone jack with cotton swab by inserting the swab in, no liquid applied.
2. Then Blow Compress air in the HeadSet Jack (or Blow Air in the phone jack via Mouth in case you don’t have Compressed Air Blower Available) that will take out any dust or lint which might be inside it.
3. Then reboot your device & play a music on iPod or Music App & take your Headphone pin & while the song is being played insert the pin in & out quite few times.