You can also use another computers CD/DVD drive.

   If you forget your administrator password

 

 

If you don’t remember your administrator password, you can reset it using the Mac OS X installation disc.

Important:Because a user with the Mac OS X installation disc can gain unrestricted access to your computer, you should keep the disc in a safe place.

 

 

To reset the administrator password using the Mac OS X installation disc:

1. Insert the Mac OS X installation disc into your computer’s optical drive (or an optical drive connected to your computer), and then double-click the Install Mac OS X icon.
Note: If you’re using another computer’s optical drive, make sure your computer is set up for remote installation, and then go to step 3. For more information about remote installation, see:
Using Remote Install Mac OS X
 
• In the Installer, click Utilities, and then click Restart.
• When the Language Chooser appears, select your language, and then click the Continue button (looks like an arrow).
• In the Installer, choose Utilities > Reset Password.
• Follow the onscreen instructions to change the password.

 

Be sure to change the password for your login keychain to match your new account password so your keychain is unlocked when you log in.

In case you don't know how to use Remote Install read this first.