The answer to 'how to fix circuit breaker' is to first identify the cause of the problem. This typically involves resetting or replacing a tripped circuit breaker. Start by locating the circuit breaker panel, which is usually in the basement, garage, or utility room. Flip the switch on the tripped breaker to the 'off' position, then back to the 'on' position. If the breaker trips again, there may be an issue with the electrical circuit or device connected to that breaker.
If resetting the breaker doesn't work, you may need to replace it. Turn off the main power to the home, then use a screwdriver to remove the circuit breaker from the panel. Install a new breaker of the same amperage and type, and restore power. If the new breaker trips immediately, there is likely a deeper electrical problem that requires professional help.