Reboot your phone.

ive restarted my phone, the wifi multiple times…..doesnt change anything

What do you mean ‘from the app’? Are you trying to use the sliders on the screen, or the physical buttons on your phone? Is this the Sonos app, or another? 

Are you saying the volume slider in the Sonos app doesn’t change the volume anymore?

Have you tried unplugging the speaker from power for a couple of minutes?

i have the sonos app on my phone and thats how i select the music im listening to on my sonos 1 speakers outside. when you have the app open the side buttons on my Iphone would control the volume…..this function no longer works and im not sure why. i have restated the phone and wifi multiple times and nothing helps. im ready to delete the app and start all over again.

From the 15.6 Sonos update:

In this update:

• We’ve removed the ability to control the Sonos app for iOS using lock screen controls and device hardware buttons. The way these features were architected do not meet Apple’s experience guidelines for developers and no longer offer a reliable control experience.

https://support.sonos.com/en-us/article/release-notes-for-sonos-s2

ok so i can no longer control the volume with my IPhone. what can i do now?

You have different options. You can control the volume using the volume buttons on the speaker, using the volume slider in the Sonos app, with a voice assistant, or with a smart remote like this.

thank you

where do i find the volume slider in the app?

At the bottom of the screen? When you’re looking at a Room that is playing music, it’s the big slider at the bottom of the screen. If you’re playing in multiple rooms at the same time, putting your finger on it will bring up secondary sliders for each room.