Huawei freebuds broken?

I have had the huawei freebuds for a long time and always found them to be really good, but for some reason the left one no longer plays music, but connecting to a cell phone does it anyway.

what can it be and how can i fix it

So a friend of mine has the exact same problem, which means that you didn't do anything wrong. If you have a guarantee for it, then definitely exchange it! Otherwise I can unfortunately not help you.