Hi, and welcome to JA!!
You need a volt meter to test a breaker, but if you do not have one, the best thing to do is swap the breaker with another breaker in your box of the same amperage, and see if it changes anything.
If you do have a volt meter, put one lead on the screw that she wire attaches to on the breaker, and the other lead on the neutral bar in the panel. It should read about 120 volts