Troubleshooting: Soldering new headphone plug
Suggests that the black wire may not be ground (unlikely, but I've seen stranger things), or that you've soldered it to the wrong contact of the new jack, or that you have a short.

Verify that you are soldering to the intended pins on your new plug.

Check also that you don't have any shorts - it's possible you've shorted left/ground or right/ground.

If that doesn't work, I'd suggest cutting open the original plug to see where each of the wires goes. This will get you to two possible options (two orientations of pink wires), try both to see which works.