This is a required 120 volt 15 or 20 amp receptacle, located with 25 feet and on the same level as A/C or refrigeration equipment, for use by service technicians. This is a Code requirement in commercial construction; one- and two-family dwelling units are exempt from this requirement (although it's not a bad idea to install one anyway).

This is most likely due to a heavy load somewhere on the circuit (not necessarily on that receptacle) and loose connections at each device location. The bad receptacle should be replaced, and each device on that entire circuit run should be checked for loose connections and tightened if necessary.

If any devices use a backstab connection, remove them and use the screw terminals instead.

Chances are when that receptacle was installed, the electrician wired the switch to operate one of the outlets on that device. This is usually done so that the owner could control a floor or table lamp from a switch by the doorway.

On duplex receptacles, there is a metal tab on each side that bridges the two hot terminals and other that bridges the two neutral terminals together so that one feeder cable can power both outlets on the yoke. By breaking the tab, you can run separate power and/or neutral conductors to each outlet on the device.

If all the circuits are on (not tripped or blown) and the receptacles are still not working, then you most likely have a loose connection somewhere in the circuit. You should check each device on the circuit (even ones that may be working) and you'll most likely find the problem.