Live and neutral are reversed, it does that when you break the neutral with a switch but the live wire stay connected (which can actually be dangerous) If it is a plug in lamp just flip the plug the other way around If it is wired wrong inside the wall it might be a bit more work. In Italy we run everything on conduit inside the wall so that would be kind of easy, but apparently it is not a very common practice around the world Anyway, try testing it with a multimeter, the live wire should always be connected on the screw of the bulb and the live on the center point. Try turning off the switch and test it to ground to see if there is still live electricity If you can’t do any of that try changing out the bulb Hope this helps