How do I access a Mac laptop without knowing the user password at start-up? Is this possible?
There's a make use of page for that
No I don't think you can easily do this with mac operating system
Yes it is quite possible. There are many ways to do so, but, if you are planning to do this to someone who does not wish for you to access their computer, it is a felony and you can spend many years in jail for hacking crimes.
Lifehacker has an article on that: http://lifehacker.com/5681710/how-to-break-into-a-mac-and-prevent-it-from-happening-to-you Good luck! :)
depending on the version of MacBook you have (with optical drive or not) then it is definitely possible to gain access. there have been several good posts here and as has already been mentioned, the easiest (best) way to gain admin access is to use a Mac OS X startup disk. If you are familiar with the command line then following the instructions about starting up in single user mode would also be a viable option.
If it is a firmware password you have to modify the RAM configuration (adding or removing RAM) and then doing a triple PRAM reset.
If it is a File Vault password you need to get the recovery key either from the user or if it was transmitted to Apple via the users Apple ID. If this is not possible the best thing you can do is format the drive and reinstall.
If it is a login password you can reset it either by booting from an installation media and use the tool provided there or in Single User mode via the passwd command. Resetting the user password will lock down the users keychain - any and all stored password won't be accessible without knowing the original password.
OS X: Changing or resetting an account password
Bypass Mac Firmware Password
start in mode single-user
Mac OS X: How to start up in single-user or verbose mode
/sbin/mount -uw /
Shutdown -h now
Have you tried MacKrack? http://www.macupdate.com/app/mac/14710/mackrack/
If you have lost your password you can use the Password Reset utility on the Mac OS X install disc to reset the account password. Just insert the CD and hold the "c" key as you boot up the computer. It will boot into the Mac OS X installer. Go to Utilities in the menu bar and choose Password Reset. You'll get a window prompting you to select the drive on which OS X is installed; then select the user whose password you want from the drop-down menu. Enter a new password save. That's it! When you reboot the computer, you can use your new password to log into the computer. BUT if you have previously encrypted your hard drive, you won't be able to see or reset the password...