Yes/No Diagnostics
Now use the Jiggle Method as follows. Have all breakers on. If any outlets are dead, plug the turned-on test lamp into one of them. Also for all the permanent lights that are dead, turn their switches on (if you can tell which way is on). You will be going around to items in different rooms to try to bother a poor connection back into being good. Since the lamp or lights will flash on for a moment when you succeed, some undistractable person needs to watch them the whole time and to let you know the moment they see this. If you have any dead outlets, now pick some other plug-in item (night light, extension cord, etc - it doesn't have to be turned on) and plug it in to one dead outlet after another, wiggling it from side to side a bit when it is plugged in. (Any flash yet?) Next do the same at WORKING outlets in the same area and in nearby rooms, especially areas closer toward the breaker panel. (Any flash?) Next remove the covers from all the dead lights' switches and from other switches within 20' of the dead area, and with a wood spoon or plastic chopstick (no metal) poke at any bundles of wires behind the switches; you'll probably have to loosen the switches' screws to do this. (Any flash?) Finally, loosen any dead ceiling lights one by one (and after that, good ones within 20' of the dead area), poking as you did at the switches. Did the test lamp or dead lights flash on during a particular action of yours?