I forgot my administrator password.....help????

http://www.psychocats.net/ubuntu/resetpassword

Basically you have to:
1) reboot,
2) select "Recovery mode" on the boot menu,
3) Select "Drop to root shell prompt" option
4) To reset the password, type

passwd your_username

***where username is the username you want to reset.
Ej: In the case, you want to reset lisa user password, type
passwd lisa

5) Then you'll be prompted for a new password.

You have a more graphical description here: http://www.psychocats.net/ubuntu/resetpassword

Hope that helps.
Buena Suerte.

Since you've gotten instructions I'll simply try to assist you with qualifying your question.

In GNU/Linux (which Ubuntu is) there is no 'administrator' account by default. You could create one if you wish but its not necessary.

In Ubuntu and other GNU/Linux distro's you have a root account. Many other distro's actually use the root account by default, NOT Ubuntu.

Instead ubuntu uses a tool called 'sudo' that allows you to use a 'user' account that has abilities that give it access to root functions. This means that when you try to run a process that requires root privileges, you run it as 'sudo',

This asks for YOUR USER password. and if you enter it correctly you may proceed. Otherwise it does not.

Just wanted to clarify this so you understand a little bit about this, for more details visit the official documentation here:

https://help.ubuntu.com/community/RootSudo