Assuming it’s this Baby Rubber Plant, you probably have root rot. Best bet is to move it to a warmer spot and avoid watering it for a bit and hope it dries out and recovers itself.

It looks like this is a commercial plastic pot inside of a decorative pot; it’s impossible to tell if it still has water and you probably overwatered. The best bet is to repot it (ignoring the advice above), cut out some of the rotten roots, and move to a new pot with a drainage hole and a watering tray. If you want to replace the soil, get some perlite/pumice (those white rocks) for the potting mix. 1 part to 1-3 part potting soil should be fine. This stuff keeps air in the soil, keeping it dryer while also lowering soil compaction (a separate issue you may find in ~2-5 years).

Repot this plant if you’re looking for a learning experience, otherwise buy a fresh plant with a draining pot / repot from the get go. I have not repotted for root rot yet, I usually opt to get a new plant and set up drainage in the first dormant season (fall/winter).

I’m glad I got local runners set up already. Beyond that, it should be painless to migrate my projects over, when I get to it that is.