It looks to me like the the plant is in a heavy black mix -- kalanchoe should be in a well draining mix containing 1/3 sand/gravel.
Also and more importantly, it looks to me like the plant is in a plastic pot that is slipped inside a decorative container which probably doesn't have holes -- is that correct? If this is the case, it's very easy to overwater, with excess water filling the cover pot, and the plant left soaking in it... Resulting in root rot.
So, assuming the above, the first step is to take the interior plastic pot out of the outer container and set it in/on a shallow catch tray -- a plastic Chinese food takeout container, a sandwich/salad clamshell container, a teacup saucer, etc. If the plant is at all salvageable, then the soil needs to be allowed to dry until you don't feel any moisture at all when you touch the surface of the soil. It is sensitive to cold so a windowsill is likely to be too cold if you it's winter where you live, but it needs bright light. The plant could be placed a little way inside a south to southwest facing window. If you don't have a south-facing window, you may need to give it supplemental light. (During the winter, it's important not to draw the drapes over the plant, trapping it between the drapes and the cold window.)
If all of the stems are blackened and soft, then the plant may be too far gone, but if the plant perks up with the improved watering regimen treatment, then it may be saved, so next step would be to repot it in a good succulent/cactus mix or good potting mix that has been mixed with sand.
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