iPhone 5 only vibrates for incoming calls

Checking on another iPhone I find that music plays even with the mute switch on. Muting seems to affect incoming call ringtones and any other sounds created by an action like sending an email or message, or clicking a key if keyclick is on. The behavior of my phone is consistent with a broken mute switch stuck in the mute position, except that the software mute switch will not un-mute it. Does anyone have any observations on this?

Thanks for your response. Music and voice memos play so I guess that indicates the mute switch is not broken.

I've tried changing ringtone - a few people who've had this problem suggest this. It didn't work for me.

Not sure what the user manual would suggest - having re-installed iOS 10.3.3 I can't imagine what else it might suggest apart from the many things that people with this problem have suggested.

The problem of no sound for incoming calls and keyclicks appears to have spontaneously vanished. I have not done anything that might have affected it except for restarting a few times. The phone now rings for incoming calls and produces keyclick sounds irrespective of the position of the mute switch. No bell icon appears when I toggle the mute switch but using the Assistive Touch (Settings->General->Accessibility->Assistive Touch set to On) a screen appears with Device on the RHS. Clicking this shows a Mute option and turning this on and off does affect whether the phone makes sounds for incoming calls and keyclicks. I'm none the wiser as to what the problem may have been but pleased that it seems to have fixed itself.