The outlet quit working all of a sudden. I pulled it out of the wall and found about 75V between hot and neutral and 118V between hot and ground. How does a neutral suddenly go "bad". The house is about 25 years old and no aluminum wire.
Sounds like a classic backstab failure situation to me. Turn off the breaker that controls this receptacle, the start removing other receptacles that are out looking for a loose neutral. I suspect it will come completely out of the receptacle when you remove it from the box.
Answers based on the National Electric Code. Always check local amendments.