How to fix volume button not working on iPhone 7 Plus

hi, my iphone 7+ cannot change their volume AT ALL. ive clicked up and down volume button (obviously), checked bluetooth if it connected to anything, accessibility then making sure the volume thing stays even, and sounds and haptics on and also on for button toggle and also turned off silent mode. the button and everything works, but the volume thing just doesnt pops up and i hear anything at all. EXCEPT when i use it on headphones. it is not a speaker problem im sure because i cleaned it already. please help

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