yousefbhatti1 , Find below a couple links that may help to address your issue with no audio. Good luck. I hope this helped you out, if so let me know by pressing the helpful button.
https://recomhub.com/blog/nexus-6p-how-to-fix-volume-not-working-sound-and-audio-problems/
https://productforums.google.com/forum/#!topic/nexus/NZ921cezFjI;context-place=topicsearchin/nexus/category$3Anexus-6p%7Csort:relevance%7Cspell:false