Hi,
[br]
If the volume bar has disappeared on your iPhone 4 and there's no sound in apps, here are a few steps you can try to troubleshoot the issue: Check the physical buttons, Restart your iPhone, Check the mute switch, Adjust volume in Settings, Check app-specific settings, Reset all settings. If none of these steps solve the problem, there may be a more complex issue with your iPhone 4's hardware or software. In that case, you may consider contacting Apple Support or visiting an authorized service center for further assistance.
Read also about: [link|https://pmlforum.com/how-to-change-alarm-sound-on-iphone/|How To Change Alarm Sound On IPhone|new_window=true]