Volume bar missing on iPhone need help

I just had this same problem with my wife’s iPhone 4 with IOS 5.01. What I came across was when she plugged in her iPhone into her car audio system which recognizes the iPhone as an audio device it takes over the speaker control and leaves the speaker control locked in “Docking Station” mode as opposed to “iPhone”. The only place to change this is directly in iTunes on the device. (“Choose Which Speakers to Use” is the little icon in the lower bottom right of iTunes with a square and a triangle that points upward). What I had to do was plug the iPhone back into the car audio system and it still gives you option to select “Choose Which Speakers to Use”, I selected another option beside the “Docking Station”, unplugged the device and everything was back to normal.

stuterhay, in the end the phone continues to loose sound and the volume bar is gone. I am taking the phone into the Apple store to see what they can do. I purchased her iPhone and mine at the same time. We only have this issue with her iPhone. When I do what I described it works, but within hours of changing and correcting the problem, it goes back to the same issue. Just so you know, everything I talk about is actually on the iPhone, not in iTunes.

The image below shows the button that I describe.

With the phone not plugged into anything I get no volume or sound through the external speaker. When I select the above highlighted button I see this menu below that pops up. (Don’t pay attention to the Living Room button, I run an Apple Airport in my home to stream music to.) Dock Connector should not be selected because it is not plugged into anything at this time, therefore I get no sound out of the external speaker. I can get sound through headphones if I plug them in, but once I unplug the headphones I still get no external sound.

Once I plug the iPhone into the connector in the car that allows the music to come through, the music comes through the stereo with no problem. When I disconnect the iPhone I know have the below options that appear and with iPhone selected all external sound works just fine. Typing sounds, swooshing when you unlock the phone, volume bar appears when you adjust the volume for ringer and others. Problem is, it only lasts for an hour or so and goes away on its own with no reason why. I have even disconnected all the Airports in my home to see if there was some conflict there…with no luck. Once again, I purchased my phone at the same time as hers and I don’t have this issue at all and I plug into the same stuff and connect to the same docks and such that she does.

Have a look here...

http://support.apple.com/kb/TS2802

Also, try a Reset...

Press the sleep/wake button & home button at the same time, keep pressing until you see the Apple logo, then release the buttons...

http://support.apple.com/kb/ht1430

c00p3r can you please explain in detail how you did this? I believe my phone is having the exact same problem, but I cannot find the "choose which speakers to use" anywhere. I searched online and it said it will not pop up on my computer becuase it automatically uses my computer speakers, so how were you able to do this on your phone?

When you turn up the volume from the side button what does the screen say?

What "volume bar" are you talking about?