Inline Rotary Cord Switch Replacement Gear Rotary Switch Direct Plug-in Light Wire Switch for 18/2 SPT-2 Lamp Cord

You’ve tried a new / known working light bulb? If you’re sure it’s really the switch, they make replacement switches: https://www.amazon.com/AXLIZER-Inline-Rotary-Switch-Replacement/dp/B08YN62J75/ Otherwise, you’d be looking for an “E26 lamp base / light socket” in all sorts of different varieties. You might want to look for one that is weather rated.