If it's not showing up in the sound indicator any more, the three most likely reasons are
The plug-in got disabled/removed
A problem exists in the sound menu itself
A problem exists in communication between Rhythmbox and the sound menu
Check that the plug-in is enabled under Edit->Plugins (I think the support is integrated with the Notifications plug-in, and there are settings for it to disable the tray icon/sound indicator support, or pop-up notifications). You can also log out, wait a minute (some of the services take a few seconds to exit after logging out), and log back in. This will restart all the related services and Unity, so that if some underlying service was the cause, the problem should just go away.
did you try to remove the rhythmbox folder before reinstalling it? or removing rhythmbox with the --purge option? If not, the same configurations will be used even if you remove and install the application
Go to your home folder in Nautilus, press CTRL + H to show hidden folders, and look for .rhythmbox. Backup it to another location, then delete this folder. Restart Rhythmbox. You'll lose your personal settings, but at least you'll have a working Rhythmbox again. If you want to revert to your old settings at any point, again delete the .rhythmbox folder and put the backed-up .rhythmbox folder there.
If it's not showing up in the sound indicator any more, the three most likely reasons are
Check that the plug-in is enabled under
Edit->Plugins(I think the support is integrated with the Notifications plug-in, and there are settings for it to disable the tray icon/sound indicator support, or pop-up notifications). You can also log out, wait a minute (some of the services take a few seconds to exit after logging out), and log back in. This will restart all the related services and Unity, so that if some underlying service was the cause, the problem should just go away.did you try to remove the rhythmbox folder before reinstalling it? or removing rhythmbox with the --purge option? If not, the same configurations will be used even if you remove and install the application
Go to your home folder in Nautilus, press CTRL + H to show hidden folders, and look for
.rhythmbox. Backup it to another location, then delete this folder. Restart Rhythmbox. You'll lose your personal settings, but at least you'll have a working Rhythmbox again. If you want to revert to your old settings at any point, again delete the .rhythmboxfolder and put the backed-up.rhythmboxfolder there.