I'm so excited right now. My keyboard and trackpad were going on and off on my laptop, so i did the usual recommended things, resent PRAM, tape down the cables, etc etc. It went away for about 6 months, then BAM, it went, completely, could not get it back.

Desperate for solutions, a technician said it might be the entire top case assembly. It's the thing the keybaord sits on (includes the power button, trackpad, and other things). He recommended i replace it and see what happened.

So, i went on ebay (yes, ebay), and searched for the part number (922-8036) for my Rosemary edition Macbook Pro 15'' Core 2 Duo. There were a lot on there, i got lucky and found one new for 80 bucks plus shipping. Got it, and used ifixit.com's keyboard tutorial to open up my laptop (although the process was familiar to me by now), remove the keyboard, and transplanted the little chip that's to the left of the trackpad (when the top assembly is upside down, the new one i got didn't have that with it). After installing it, turned on my laptop, and VUALA!! Keyboard and trackpad back working.

Sometimes, resetting PRam, all those things, can't fix it for good. Sometimes the top case assembly is just...bad. For 80 or so bucks on ebay, grab a new or like new assembly, and just fix your laptop.

Try the easy stuff first, but when all else fails, the source must be hardware.