Try this procedure first.
You have a circuit with dead outlets and maybe some dead lights on it or you’re experiencing flickering on a circuit. You will need a 2 wire voltage tester to check the outlet. A Multimeter or a Volt/Con are suggested. I prefer the Volt/Con because there are no settings to make, it does continuity and is audible. Success begins with knowing what you’re looking for.
1] No voltage reading between the hot and the neutral or ground indicates an open hot.
2] No reading between the hot and the neutral but 120V between the hot and ground and 120V between the neutral and ground indicates an open neutral.
3] No continuity between the neutral and ground – Check for tripped GFCI device first
4] If all the branch circuit breaker are on you have a bad connection on the hot or neutral wires. The usual cause is a bad connection, either a termination on a device or connection in a wire nut.
Over the years I’ve found the easiest way to locate the opening needing examination and correction is to wiggle the devices.
5] The first step in this exercise is to get a lamp to act as an alert. Make sure the lamp works and in the on position. You may also use something like a vacuum cleaner or blow dryer, for an audible alert. Don’t use anything electronic, like a radio.
6] Plug it into a dead outlet.
7] Now with a cube tester or any plug you will need to go to all the dead outlets and any live outlets in the area, insert the plug and wiggle the device side to side slightly. Watch the test lamp or listen for the other alerts as you wiggle the devices.
If the loose or bad connection is present the wiggle action may make it contact briefly and the lamp or the other things will alert you . Having found the suspected outlet all that is left is to correct the bad connection.
If the device is a push back wired device, this probably is the cause of the circuit failure. All wires must be terminated under the screws. Also you should never put more than one wire under a screw.
This troubleshooting procedure works in most cases and won’t have you open boxes un-necessarily. Keep in mind that the problem is in one of two places in the circuit, either in the first dead outlet or the live outlet just ahead of it.