Having same issue with ipad3. It appears to be an auto muting issue. If I restart iPad3 (6.1.3) and quickly open task bar, I can see volume slider. Wait a couple of seconds and bang it disappears.. Restart again, quick play a song via music, everything fine for about 2 seconds, then it mutes, again slider in music app disappears. Restart again, bring up keyboard press keys randomly, can hear all the keyboard clicks for about three seconds then silence. Think this happened during 6.1.2to 6.1.3 upgrade I think there used to be an auto mute feature in 5.1, I think somehow this is old feature is being invoked, but that option no longer available via settings... If I plug headphones in, volume sliders will reappear while headphone is present. Have tried full reset, but no luck, and I'm not confusing the auto mute auto lock functionality either...
Not sure how current this thread is, but i've been on 6.1.3 for a few weeks and this issue popped up quite suddenly 2 days ago. i've gone though some basic steps with my carrier but that seemed to make it worse. The battery get extremely hot when anything data is engaged and it frequently drops 3G and wireless connections when data is being used. I've basically disabled everything but Safari and Facebook and it's still draining my battery extremely fast despite no actual use.
There seem to be significant problems with this version of the iOS (6.1.3). I have had problems with virtually every aspect of the iPhone 4 since the update. I also noticed that my car's iPod control no longer works with this version of the OS. I'm not sure just what is supposed to be so great in this last upgrade that it required breaking the existing systems. Apple seems to be completely stonewalling everyone about it as well. Half of the time when I look at my phone I have the Music volume control floating at the top of the screen. Nothing works as well as it did before and I seem to be unable to restore to an earlier version, at least without risking losing too much data, not to mention time in the process.
I had an Android phone before the iPhone and I thought it was a better, if not as pretty a phone and interface. I had much less trouble with it. My wife just got a Samsung Galaxy III and loves it. It has been completely reliable and she isn't tied to iTunes to boot. Apple had better step up their game and fix these problems or my next phone won't come from Cupertino, well really from China. If Apple is so great why has their stock lost about 20% of its value in the last year? I know I'll get hate mail for this one, maybe even bounced off the forum for heresy.
Maybe you all have already tried this. I had a similar problem with my iphone 4s, i.e., no sound, only vibrating. My problem was that my bluetooth was on and the sound went directly to bluetooth. What stumped me was that the incoming call ringer DID sound. When I turned off the bluetooth, sound was restored to my handset.