You have already had issues with one outlet before, and now another outlet has malfunctioned. Even if you track down the problem this time, you're likely to have the same problem again with a different outlet later. Electrical problems like that can be a potential fire hazard.
I would simply replace all of the outlets on that circuit. A box of 10 outlets is less than $20 at Home Depot or Lowes. It shouldn't take more than a couple hours to replace them all and you can inspect the wiring at each outlet in the process. Personally, I would replace ALL of the outlets in the house, but at least do that one circuit. I usually buy new cover plates too so the installation looks clean when you're done. I would probably replace the wall switches too so everything is updated at the same time.
Verify the breaker is off in the panel and put a piece of tape over it and/or lock the panel door to make sure no one else turns it back on while you're working. Then use a multimeter or a tester like
aja8888 showed to make SURE the power is off at that specific outlet before you start working on it. Many houses are wired weird so don't assume that all living room outlets are on the living room circuit. TEST before working on them.
DO NOT use the back stab terminals, connect the wires securely using the side mount screws. Remember to wind the wire in the direction the screw turns so the connection tightens as you tighten the screw.
As for replacing the breaker, it's not that difficult if you have a newish panel with a main circuit breaker. Turn off the main breaker to disable power in the panel, then remove the panel cover and pop out the current breaker. Make SURE the new breaker is the same brand and style as your existing breaker. Move the wire from the old breaker to the new one, then pop the new breaker in.
Oh, and as for the 120V shock vs 240V killing, don't be fooled. You can die just as easily from a 120V circuit as a 240V circuit. It's the current that kills you, not the voltage. A static electricity shock can be thousands of volts but the current is low so it doesn't kill you. It only takes about 100ma to kill you so you can certainly die from a 120V 15A circuit.
https://www.asc.ohio-state.edu/physics/p616/safety/fatal_current.html