Wecime to AC.
The volume setting for the phone ringer is in Settings, Sounds & Notifications, if that's what you mean.
If the ringer has just stopped working, first try a Power Off and Restart. If no go, try a Cache Partition wipe. If no go, try Safe Mode....if that fixes it, the problem is being caused by a third-party app which you will have to identify and uninstall.
If still no go, get back to us.
Posted via the Android Central App