During the Christmas period, I noticed that the keyboard of my Macbook Pro (13", mid 2009) was no longer lighting up. I tried everything, from the obvious (push F6 a few times) to the less obvious (boot into Windows). Normally you'd get the onscreen transparencies when you push F5 and F6, but in my case those keys did nothing, no transparency, no light. They still worked as regular F-keys, and I'm pretty sure my ambient light sensor still works. But as switching the operating system didn't seem to help, I assumed it was a hardware issue. This inevitably led to me open up the poor machine and make trial and error adjustments with the horribly tiny ribbon cable, resetting the SMC and PRAM each time for all the good it did. I even bought a new backlight component on eBay and plugged it in, but I still couldn't coax any light out of the thing. I'd almost given up when I tried Lab Tick on the off-chance. And somehow, that brought the dead backlight back to life. It didn't even ask for system permissions! The F5 and F6 keys still don't work to adjust it manually, so I'm stuck using Lab Tick to dim the backlight if I want to watch a movie. I'd be interested to know what's stopping the F-keys from working, and how to fix it, since I now know it's not a hardware issue. Any ideas? TL;DR? Can't adjust the backlight with F keys. Not sure why, but it's not a hardware issue. If you found this on Google because you have a similar problem, try Lab Tick.