Test the screws holding the light switch in place with the non voltage voltage tester. No power to a light switch wiring for a the light switch.

Swapped Out Light Switch And Now Wires Have No Power Home
No power to light switch. Shut off the breaker for the circuit that the light is on. Twist the set of wires together at the receptacle box and check the wires at the panel box end with the continuity checker on your voltage meter. Start by examining the wiring in the electrical box where the ceiling fan is located. When testing electrical circuits you must always be sure of a proper reference ground. What you are measuring is a floating voltage. Disconnect the wire from the circuit breaker and the receptacle.
A switch should be on the hot not the neutral. Let say you have line hot going into a light bulb and the switch is connecting to the neutral side of the light bulb. Compare the wiring to the ceiling fan wiring diagrams found at the links i have provided below. If the light had been flickering however youll probably need to go a bit further. No continuity indicates a break in the wire. This is the simplest solution youll want to try first that may fix the issue.
The home installation usually has the black hot wire going from one switch to the next switch maybe to a receptacle and on to another switch. If it lights up you still have power running through the circuit and you havent shut off the right breaker. While the nintendo switch console is placed in the dock the lcd screen will automatically shut off as the software application will be displayed. Switch the main circuit breaker to the off position. Compare the wiring to the wires found at the light switch in the room. If you only have one cable to the switch box this means that there will be no neutral in the box.
Diagnosing light switch problems. A switch is put on the circuit to turn loads usually light fixtures on and off. If the light switch isnt working at all there may be no power to the circuit. Unscrew the switch cover and remove it. Why would a switch read 0 volts when the light is turned on and 120 volts when the light is turned off its actually quite simple. Nintendo switch systems do not have a power light.
Identify the wiring for a the light switch. Make sure the breaker to the switch is on in your breaker box and determine whether there are any other tripped outlets and switch them on as well. The problem may be a loose connection or a tripped wall outlet. Although not legal a switch on the neutral is sometimes done by amateurs. You say that the box is not grounded so you will not have reference ground for your meter.