This question already has an answer here:
I just got my first Raspberry Pi 3 few days ago, however I've encountered some problem. (Please note that I am VERY.NOOB)
So when I've got a brand new Toshiba 64GB SD card hoping to do the job, properly formatted it, mounted the image (I've tried NOOB, Raspbian and MATE) and everything set up. The OS works completely fine until I reboot the Pi. Basically things wouldn't work after I turn it off. The boot sequence was halted at "Unable to mount root fs on unknown-block(179 2)".
I've followed some comments around the forums saying I should hold "SHIFT" and make changes, however the SHIFT doesn't do anything for me.
I'm using a MacBook Pro if that helps.
Thank you so much!
I tried the answer from the suggested solution, as I have mentioned, I can't get "Start the Raspberry holding the Shift key" to work, it is not reading my keyboard unless I'm in the GUI