I installed new electrical in my basement. An outlet was being used and went out. The breaker didn't trip. I flipped the breaker anyway, and nothing is working. Not the lights or the outlets that the circuit is connected to. Could it be the breaker itself that needs to be replaced?

Measure the voltage output at the breaker. My guess would be a disconnected wire in the circuit. Did you back wire the outlets or twist the wire around the screw?

"New electrical" WHAT, I give up.

What did you install? Did you install a new branch circuit, a receptacle outlet, a secondary panelboard?

Was the circuit working before you installed whatever you installed? Can you help me please?