To start (if both laptops are identical) take a look at this video:
https://www.youtube.com/watch?v=bhyi4_i7yOA. It seems that the jack is a cable not soldered.
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if they are not identical anyway the video will give you an idea of how to get to the jack.
if it is a cable it has a sticker with the model number.
if it is soldered you best shot is take it to a repair store.