i found this one does it work i dont want to screw up my computer thanks :)
It sounds like the system is set for automatic login. Ask the previous owner to tell you the password... unless you found it on a park bench.
You can boot to an OS X install DVD and go past the first screen, to select main language. Then under the Utilities menu (or Installer menu on older versions), choose %26quot;Reset password%26quot; and then select your account name, not %26quot;Administrator%26quot;.
If you don%26#039;t have any install disc, you really need to buy one. It is like driving without a spare tire. In the mean time, look in the Users folder for the name of your home folder. Write it down and follow these steps:
1. Boot into single user mode (press Command-S at power on)
2. Type fsck -fy
3. Press Return
4. Type mount -uw /
5. Press Return
6. Type launchctl load /System/Library/LaunchDaemons/com.apple.鈥?br>
7. Press Return
8. Type dscl . -passwd /Users/username password (replacing %26quot;username%26quot; with the targeted user ((name of your home folder)) and %26quot;password%26quot; with the new password)
9. Press Return
10. Type reboot
11. Press Return
Last resort: delete a file called %26quot;.AppleSetupDone%26quot; (the dot makes it a hidden file in UNIX). Then when you restart, the Mac will open the same setup program that appeared when your computer was new. You can create a new account from scratch. After you are logged in as the new admin user, you can go to System Preferences %26gt; Accounts and reset the password of your old user. That%26#039;s a bit inconvenient but, in theory, nothing is actually lost. Then you can log out, login as your old user. Then you can go back to System Preferences %26gt; Accounts and delete the new user.
To delete this secret file, restart and hold two keys together: Command key (鈱? and the %26quot;S%26quot; key. That starts the Mac in %26quot;Single-user mode%26quot;. You%26#039;ll know you are seeing single-user mode because the screen will fill up with white geeky text on a black background. Release the two keys when you see this. Wait until the last line says %26quot;sh-2.05a#%26quot; or something similar. Then go ahead with the steps below. Don%26#039;t type the %26quot; marks and be careful to type the spaces in %26quot;/sbin/mount -uw /%26quot;.
Type %26quot;/sbin/mount -uw /%26quot;
Press Return. (Nothing appears to happens, no problem. Also, you will see # again. That%26#039;s fine; ignore it.)
Type %26quot;rm /var/db/.applesetupdone%26quot; (The normal format of Mac OS doesn%26#039;t care about upper case.)
Press Return.
Type %26quot;reboot%26quot;
Press Return. (Now stuff appears to happen. You will finally get past the %26quot;Welcome%26quot; in a dozen languages and then you can create a new admin user. It should be a different short name from your old user. A few screens later, you come to the registration. Just choose %26quot;later%26quot;. It doesn%26#039;t come back later to nag.
After you have completed the new user, open System Preferences %26gt; Accounts and delete the old user. It will put all old user%26#039;s data into a disk image and put that into a %26quot;Deleted Users%26quot; folder. If you don%26#039;t need that old user data, trash the disk image.|||Yes, it will work.
