need help with my macbook please help!!!
i recently was prompted to update my macbook computer and after loading the new update it said would need to restart computer. so it restarted and started loading the new update and was about 90 percent done when it said failed and froze i restarted the computer and now all it does is sit there at the start up screen and does nothing. i was told by geek squad that my operating system (snowlepord) might be corrupted so that i would have to reinstall snowlepord again. he said there are hot keys to pull up the configuration menu were i would be able to reinstall my operating system but i have no idea how to bring up that menu any information would be very helpful they wanted 100 bucks just to look at my computer. please help!