how can i select an option when reinstalling my OS after erasing my disk? i have the two options of "macintosh HD" and "recovery mode" with "back" and "install" on the bottom but i cannot select anything. please someone help! My OS is Yosemite and my macbook pro is 2008. Like i said, i've erased my disk and i just want to reinstall my OS. i got down to the page where it says to install but it won't let me select anything whether i'm using the mouse or pressing the space or enter bar or arrows, etc.