Well start by using a different device (iphone, ipod, or mac): It could very well be the jack, rather than the deadphones.
next, lace the traces with solder: they could be worn down, and a thin layer of solder could make the connection good again.
if these two options dont work, you have a physical break in the headphones, and the amount of labor involved in fixing them, is worth FAR more than just buying a new pair for 40$. this can be found here. https://www.apple.com/ca/shop/product/MNHF2AM/A/apple-earpods-with-remote-and-mic?afid=p238%7CsflHk1Tl7-dc_mtid_1870765e38482_pcrid_142913545083_&cid=aos-CA-kwgo-pla-brand--slid--product-MNHF2AM/A-CA