First you'll need to determine if the lights are 12 v or 120 v. Being 'under the microwave' could be they are 120 v. If they are 12 v, remove the bulb and start shopping. Many options available, in many colors, measured in kelvins. Don't go by descriptions like, 'cool white' use the kelvin temperature for more accuracy. Also pay attention to lumens, or the amount of brightness they give off. Again, don't buy if they just say, 'bright.' Match your socket plug style with the offerings of many on line sellers.