I get called every so often by a friend of mine who is an apartment maintenance guy. He will get calls from friends with dead outlets in their house. I always tell him to look for tripped GFCI's. The last time, the HO had scabbed a string on basement outlets onto the load side of a kitchen GFCI receptacle hiding behind a bunch of crap on the counter. Took him awhile to track that one down.
Almost had my own troubleshooting job. I'm in the middle of a bathroom gut job. Apparently stackers didn't exist in 1977...there were 5 12-2 NM's laid out across the face of the 2x4, and a screw that missed the stud grazed the jacket of the NM that was hard-up against the drywall at the edge of the stud.