Hi, I have an early-2011 macbook pro 13'' and I was using it normally when everything froze. My word and excel froze and every time i tried opening chrome it kept crashing. I figured I could just hold the power button for 5 seconds to turn it off and when I turned it back on I was prompted with the OS X Utilities window, and when I try to run my computer normally my hard drive isn't available, as if my startup disk completely disappeared! I tried holding option while booting but it just shows the Recovery HD disk, not my local disk. Please help! I have no backup of my computer anywhere and have important school material on it! Thank you