problem is it took you some time to realise it didnt work.

what if the seller genuinely thought it was fine & now thinks you fucked it up somehow?

also people have garage sales when they are moving & it might not even be their house even if they are still there.
what you did was the same as buying a car without test driving or even staring it up, so if seller wont give your $ back i think you should just wear it.