Recently I have had an error from the launcher claiming that the OpenAL library is unavailable, and due to this the game is changed to No Sound mode. Closing and reopening Minecraft or the Launcher does not help. This did not use to happen, but I have not changed any sound related settings. This does not happen every time, although when it does, only deleting and re-downloading the 1.9.2 version files will fix it.

The section of the launcher log reporting the issue:

AL lib: (EE) MMDevApiOpenPlayback: Device init failed: 0x80004005
AL lib: (EE) MMDevApiOpenPlayback: Device init failed: 0x80004005
[17:16:30] [Thread-5/ERROR]: Error in class 'LibraryLWJGLOpenAL'
[17:16:30] [Thread-5/ERROR]: Unable to initialize OpenAL. Probable cause: OpenAL not supported.
[17:16:30] [Thread-5/WARN]: ERROR MESSAGE:
[17:16:30] [Thread-5/INFO]: Could not locate OpenAL library.
[17:16:30] [Thread-5/WARN]: STACK TRACE:
[17:16:30] [Thread-5/INFO]: org.lwjgl.openal.AL.create(AL.java:156)
[17:16:30] [Thread-5/INFO]: org.lwjgl.openal.AL.create(AL.java:102)
[17:16:30] [Thread-5/INFO]: org.lwjgl.openal.AL.create(AL.java:206)
[17:16:30] [Thread-5/INFO]: paulscode.sound.libraries.LibraryLWJGLOpenAL.init(LibraryLWJGLOpenAL.java:164)
[17:16:30] [Thread-5/INFO]: paulscode.sound.SoundSystem.CommandNewLibrary(SoundSystem.java:1576)
[17:16:30] [Thread-5/INFO]: paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2572)
[17:16:30] [Thread-5/INFO]: paulscode.sound.CommandThread.run(CommandThread.java:121)
[17:16:30] [Sound Library Loader/WARN]: ERROR MESSAGE:
[17:16:30] [Sound Library Loader/INFO]: Could not locate OpenAL library.
[17:16:30] [Sound Library Loader/INFO]: Starting up SoundSystem...
[17:16:30] [Thread-7/INFO]: Switching to No Sound
[17:16:30] [Thread-7/INFO]: (Silent Mode)