This video shows how to replace a earphone jack with mic (4 pole mini jack)
This type of soldering can be quite tedious because of the mini jack's small size and to solder on the tiny slots needs a lot of control over the hands and hell lot of a patience:)
Even the most expensive headphones can suffer from sound problems due to frayed electronics in the cord. In this situation, mono sound will come out of one headphone instead of stereo sound from both. Rather than replace the headphones/earphones, there is a potential low-cost alternative. By repairing the wires and re-soldering them to a new headphone/earphones jack, you will have the sound that you love and you will be able to keep your favorite headphones.
MX EP Stereo 3.5 mm with 4 Pole Jack product Link: