1st floor receptacles on what circuit?

I'm pretty sure these receptacles both worked in the past -- one more than the other.
The other, behind a couch, when I took the cover, the receptacle pretty much disintegrated --like the plastic had become too brittle over time. I presumed that explained why the outlet had no juice.

But when i tested the supply -- it had no juice either. On an adjacent wall there is also an outlet that is dead. That's the one I'm pretty sure did work at one time. Not today. It has supply (dead) and continuing romex (also dead).

Problam is, after trying all the likely circuits (off and then on again) and ditto some breakers that aren't labeled I get no juice on any of the wires. It strikes me the panel won't help me because I don't currently ('scuse the pun) don't have juice in the receptacle(s).

Down in the basement I'd hoped to find the supplies -- but (19th century old house) nope, nothing coming down from the joists.
Weirdly, each dead outlet has a outlet opposite it in an adjacent room -- they both work and are grounded. I haven't proved what circuits they're on (same or otw).

As I write this I realize I need to see what wires are in those receptacles and if they're connected/live/dead etc.

Presuming, the live outlets wiring is secure and fine -- is there _any_ way to suss out why a supply is dead without removing drywall from receptacle -- to ceiling (and then to who knows where)?

there can be many outlets or lights and switches on one circuit. You could have a poor or bad connection in any box in the circuit as the power just goes from box to box to box.
Some times you can have outlets that are switched in living rooms as the switch controls the lamp in the corner.

hmmm. thanks Nealtw. There is a 3-way for a ceiling fan. Maybe, just maybe that switch controls those outlets too. Doubt it but maybe...

all right, its not the ceiling fan switch and I know I used the outlet that appears to pass the power on to the next in the past (vacuuming)
I know its a stretch (since its just two outlets and there are others closely adjacent on the other side of the wall - but what if the breaker itsself is bad?
Anybody got a quick list of how and what to use to prove out a breaker? years ago I wouldn;t think of messing with breakers, but i've brought my game up a bit...

Sure, with a VOM. Remove the dead front panel on the service and check the output of the breakers, with them on.

However, you'll need to open the recep. boxes, on both sides of the wall, and conduct voltage and resistance checks to confirm continuity.