I had lost power to half our electrical and no breakers tripped. The problem was a bad main 50 amp dual breaker which would flicker electricity on two house circuit paths (kitchen and bathroom) until it went dead, and the other side was good, but would brighten or dim. If your problem is only a room, then its probably as suggested by the previous threads. If it is more widespread, it could be one leg of the electricity, or a sub-panel breaker. I originally tried to reset GFCI outlets with no success (no power at those outlets) and it took a week to finally diagnose the problem. Bad breakers are apparently rare. With one room, also consider a bad breaker in the sub-panel, if your panel is very old, like mine, which is about thirty years old.