If they're the "puck" lights, they have integrated bulbs.
This store (LINK) sells replacements, but I suspect you won't get a choice of a different brightness or color and still have them fit your existing fixture.
Replacing a puck is not at all a hard job. I replaced the glaring "reading light" above the head of our bed with a dimming light in a warmer color.
Way better. The screwhole pattern didn't match, but it's all behind the light anyway.
Link to the product
Link to a posting with photos and a video link of it in operation