Your troubleshooting is limited checking things from the outlet to the junction (usually in one of the closets). Unfortunately, it's sometimes impossible to run new lines in apartments, and you may just have to run a line on the floor from another room to make up for the bad outlet.
The cable company does NOT own the wiring throughout the building, and you do not either. The apartment complex does.
It is my experience that some complexes take responsibility for bad wiring and will pay to have someone replace or run new lines. Other complexes will tell YOU to contact someone and YOU to pay to have it fixed. Your results may vary.
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