I have a dead circuit in my house, went out all at once circuit breaker is good,what could it be?
It sounds like you have a loose wire somewhere in the circuit. These things can be hard to track down. Somewhere in the circuit, there is a break. It could even be at a device that is working, because it could be the wire leaving the working device that is not working.
Check all outlets, switches, and lights. Check the wire nuts, because the wire could look connected, but not be. Especially check any outlets and switches that have the wires pushed in the back rather than screwed to the sides, because sometimes these fail. You may want to get a circuit analyzer for under $10 at any home center which will narrow it down to the white or black wire.