My earphones suddenly lose sound in one ear

I have been using the Apple earphones for about 4 months, the one that go with the iPhone 11 box when you buy it. Today when I was playing game, the sound in one side suddenly lost even though it was still good seconds ago. I have never done anything that could damage the earphones, like let it be in the water or such. I thought the problem came from my iPhone 7 at first, but even when I restarted my phone, my earphones still had not been back to its normal state. I tried to use other applications too, but it seems like the problem really does come from my earphones, not my phone.

I have been using Apple earphones my whole life, and my previous ones surely lasted longer than this. Is there any way to fix this? Thank you in advance.