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Just pop in your restore DVD and boot up to the install screen. Choose Utilities from the Menu Bar and choose Change Password.
 
No i for got my password to my main account. So overtime i try to install or uninstall anything it ask for the password and its not working.

Ok i fixed it.

Did the method I linked to work then?

You did read the first part only I guess, whereas the second part (of four) explains what you want to do.
(Resetting the original administrator account password)
 
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