Using same earbuds from 2 year's, now mic not working well. Can you help me

I bought them less than 3 months ago and almost I have not used them, I stopped using them for a while and left them stored in the charging case and now the right earphone does not work so I left it charging for a long time and I have tried to synchronize it as indicated the manual and other tutorials and it has not been possible.

pesimos me salieron los 2 juegos,suenan muy bien pero el derecho me falla mucho,se corta a cada rato...