Non-functional AirPod with charging issue

I am a huge fan of AirPods and I wear them all the time! I lost one of my AirPods for some time and when I found it, it would charge but could not connect to my phone. There is no sound coming from it even if I play the find my iPhone for my AirPods. I’m not sure why this occurred, is there any way I can get a replacement? I know there is such a thing like a warranty, I used to have a different case of AirPods for this I had the warranty but then I lost the case. I went into Apple and they said they can’t do anything about it so I purchased another case(current) and this happens. Anything would help!! I might just end up throwing it out help I don’t know what to do!

[Re-Titled by Moderator]