please help me! during revise my macbook system administrator, i just did follwing one of comment from internet. press and hold Apple button+S black screen with white text mount -uw/ rm /var/db/.applesetupdone shutdown -h now after above commed the computer appears a big "welcom". It looks like my macbook was reformated which i didn't expect. did i lost all data? is that any way to go back? thanks.