One socket is dead

Check the obvious

Try another appliance in the socket, and check the trip switches. If the socket has a switch, make sure it is on. If other sockets in the room are also dead, it is the circuit, not the socket.

What it usually is

A loose connection behind the faceplate, a broken ring, or a damaged cable from a picture hook or a screw. A warm faceplate or a fishy smell means a connection is overheating. Switch the circuit off and ring.

The fix

I test the circuit, find the break and put it right, then test again so you know the rest of the ring is sound. Usually a short visit.