Sounds like you have a loose connection or bad breaker,
You said you had no power at the load side of the breaker.
Now all of a sudden its come good again,
What have you done ?
If it has come good after you have switched it off and on again,
this suggests that the breaker has either tripped for some reason
or is faulty in some way.
If it is working again, just monitor the breaker.
Is it getting unduly hot,
Make sure the conections on the breaker are good.