Hi guys, I haven't been able to find this anywhere on the forum so here goes: My Macbook Pro (mid 2009) won't boot. I get the prohibitory sign/question mark on grey screen, and nothing happens. I've tried resetting SMC, NVRAM/PRAM, booting in safe mode and recovery mode, and just letting the damned thing have a good nights sleep. Nothing seems to be working though. So I've come to the conclusion, that I need to reinstall my OSX, but here's the problem: I just updated to Mavericks and I only have Snow Leopard on disc. Can I boot and install snow leopard anyway? And what about my data will it all go? I've tried to insert the Snow Leopard disc and pressing "C" during start-up, and it seems to be working. The question is whether or not to go on with the installation. I wouldn't want to lose my data. Any professors online?!