Room Full of Working 120V Electrical Outlets, Except One Doesn't
First, the non-working outlet is likely connected to a wall switch or a junction box, which may have been disconnected or even removed and covered over. Trace the wiring, either with an AC circuit tracer or metal/stud finder to find the junction box.

Second, how are you measuring the voltage hot-ground? A high-impedance multimeter may be picking up AC capacitively coupled from a parallel line, and the ground could be floating. An outlet tester might be better. That said, if the ground is floating, perhaps due to poor connection (or no connection) in a junction box, that is a serious safety issue; trace it as above and fix it.