I tried to reset my lost password using the steps on this website. http://www.macyourself.com/2011/08/20/how-to-reset-password-for-mac-os-x-10-7-li on/
I messed up but im not sure on what. now its stuck on the grey loading screen. what do i do now?
Resetting or changing a password:
For Snow Leopard or earlier: http://support.apple.com/kb/HT1274
For Lion or later: http://support.apple.com/kb/HT6022
This is also useful:
http://www.macworld.co.uk/ipad-iphone/news/?newsid=3463233&olo=email
If it's running Mac OS X 10.6.8 or earlier, insert a Mac OS X install DVD, restart with the Option key held down, click on it, and use the Reset Password utility.
If it's running Mac OS X 10.7 or newer, restart with the Command and R keys held down, open the Terminal, and use the resetpassword command:
but my computer wont even boot so i cant change anything
Read the instructions again.
How do i get my iMac to boot after unsuccessfully trying to reset the password?
