Volume problem

[Ca123ish]

I'm having trouble turning up the volume on my phone, I can do it but only when I'm using the phone in a call.
But when I want to use the music or pandora app or even YouTube
The volume bar is gone and all that's there is a message saying no volume available

 

[Thomasjtsi]

I would suggest performing a Hard Reset of your device. Hold your Home & Lock buttons, together, for 10 seconds. Then release both and your device will reset itself. Don't worry though... there won't be any loss of data from your device.

 

[bab2010]

It seems like the iPhone is thinking that it's connected to a dock connector or it have a jack in, try blowing some air in the dock and in the jack port and see if it helps or not. My iPhone will display that message only when i connect a cable to it and mirroring to the tv, or connect in a jack of a loud speaker.