Sorry to just drop into the conversation. I was browsing through forums after having problems with my volume, and my predicament landed me here. I just thought I would toss in a bit more information.
Pardon me if I am completely out of line, as I understand the heading of this post is dealing with HTC One specifically. I have an Android 4, and my OS is only at version 4.1.2 Jelly Bean (Verizon carrier). If I should take this post and issue elsewhere, I am more than happy to relocate it of need be. I'll continue just in case posting here is kosher though, as it may interest some to know that this is a more widespread problem.
Today I began having problems with my volume control. After being told that I had been sent several texts by a family member, which I did not hear, I checked my phone out. All use of the physical volume control was gone. I could push the volume down and the volume bar would appear on my screen, but not move, and make no sound. After playing with it for some time, the on screen volume bar seemed to respond to my clicking the physical volume button on the side of the phone rather than holding it down. Single clicks would intermittently move the on-screen bar, but still...no sound at all. I could take the bar down to vibrate, and the phone would vibrate, but clicking up any higher would offer no audible response.
Miraculously, After one seemingly useless restart (after which the volume problems persisted for about a half hour), the volume has just started working again. All use of the physical volume bar, be it clicking it up or down or holding it works perfectly fine. Pardon me for saying it, but this was certainly a WTF moment.
While the issue seems fixed, I just thought it might be useful to someone out there to know that this earlier version of the OS (again, 4.1.2) is having problems as well, in addition to the later versions that each of you in this thread are discussing. Hopefully we can get these major issues with all versions of the Android OS taken care of with proper attention from those programming them. -_-
Best to all here, and here's to figuring this out.