I have a CFL in the bathroom that went out on me. I’ve been too lazy to change it because there are other bulbs that are working. Well after a couple weeks, it magically decided to turn back on. It’s nowhere that it would be jostled or anything, so I found that weird.
Micro vibrations, jet flying over, truck driving by, or maybe the other lights in the fixture vibrated the “broken” one enough to screw it back in. Did you know CFL bulbs can unscrew themselves from the vibrations and heat they make? Also change in temperature could cause the metal to expand or contract causing the bulb that unscrewed itself to make contact again.