Sounds odd - Power wiring is usually organised in a Ring Circuit to save having big fat expensive cables. If there was a broken connection in one socket the power could still come from the other side of the ring - perhaps you have two broken connections?
Pull the fuse or throw the breaker and remove the face plates for the wall sockets. Inspect the cables for a good connection. If you find one and repair it keep checking all the other downstairs sockets for the second fault - might even be in another room.
It is quite possible that you have lived with one broken connection for some time without knowing it - when the second bad contact happened both faults together isolated the power in your living room - but that's a guess.
Peccavi, January 2009
