Wire colors are not standardized. They even differ among models of the same manufacturer. The only way is to test against the plug that is being replaced. Hopefully most wires still connect to the plug contacts, so a process of elimination can be used. Typical colors are red, blue, green and no color. Ground is usually no color, and sometimes there are 2 grounds (e.g. for ‘zipper’ style wires). The contacts for most phones are as follows (from tip to outside barrel): Right, Left, Ground, Mic. My Samsung S3 cord was very strange: red, green, no color and 2 black wires. One black was Ground, the other was MIC. Soldering requires a magnifier and a fine tipped iron.