The answer to 'why is my junction box outlet not working' is that there are several common causes, including a tripped circuit breaker, loose wiring, or a faulty outlet. The symptoms you may notice are no power to the outlet, sparks or burning smells, or the circuit breaker tripping when you try to use the outlet.
Some possible solutions are to first check the circuit breaker and reset it if it has tripped. You can also try tightening the wire connections in the junction box. However, if the outlet itself is damaged, you may need to replace it. If you're not comfortable working with electrical components, it's best to call a licensed electrician to diagnose and fix the issue safely.