First find out whether the problem is one device, one outlet, or a group of outlets. That pattern is more useful than guessing which part to replace.
Start with what you can observe
Try the unplugged device at another known-working outlet only if its cord and plug are undamaged. Note which nearby outlets still work. A wall switch may control part of a receptacle, so check the normal switch position. Do not remove the faceplate or receptacle to investigate.
Look for upstream protection
A GFCI can protect other outlets downstream, including outlets without TEST and RESET buttons. Look for an accessible GFCI in nearby bathrooms, garages, kitchens, or outdoor locations. Read its instructions before operating it. If it will not reset or trips again, leave the affected equipment unplugged and arrange inspection.
Make a useful service-call note
Write down when the outlet last worked, which devices were connected, whether nearby outlets are affected, and whether rain or a recent appliance change came first. A photo of the intact outlet and its surroundings can help explain the situation. Do not reach into a panel or open electrical boxes to gather information.
When to stop
Heat, discoloration, burning odor, crackling, sparks, or a shock change this from an inconvenience to a safety concern. Stop using the outlet and get qualified help. If there is smoke or fire, leave the area and call emergency services.
Keep the diagnosis separate from the symptom.
A symptom is a starting point, not a diagnosis. Separate device failure, loss of supply, protective-device operation, and connection problems before selecting a repair.
ESFI: Home safety. General educational guidance for U.S. readers. Product instructions and local requirements control the installation. This first-edition draft has not received an independent technical review.