My problem was when my headphones were disconnected, there's no sound when playing music on my iPod. There's also no clicking/typing sounds. My phone still rings when someone calls me though. However, it doesn't ring when I receive text messages. No sound at all. When I press the volume buttons with the headphones disconnected, it shows the sign 'Ringer' but without the full volume bar (I hope you guys know what I'm talking about).
My solution:
The hair dryer. I did everything else, hard reset, toothpick cleaning of charging port and headphone jack, blowing into the headphone jack, sucking out air from the jack and nothing worked. I was skeptical about the hair dryer at first because I was afraid that the warm air might melt my internal phone components but I tried it and it worked. I put my hair dryer on the lowest speed, and held it about 10cm away from my charging port and then to my headphone jack. 3 seconds was all it took. I'm not exaggerating. I literally just held it at the charging port for 1 second and then at the headphone jack for 2 seconds. I switched off my hairdryer, double tap the home button and the iPod control shows up WITH the volume slider. Worked like a charm.
To prevent this from happening in the future, do not disconnect your headphones while music is still playing. I find that this problem creeps up everytime I do that. Pause the music first and then unplug your headphones.