HELP PLEASE (trackpad ibook G4 14")

I have an ibook g4 14" since 2003.
It always worked perfectly until now.
The trackpad is completely disabled.
I can not install, use an external mouse, or use the mouse track from the mac.
I found out what the problem is, then trying with the keyboard, I use ctl & O (open) and I got to the preferences.
then I type trackpad sensitivity, and it opens.
In the trackpad says trackpad gestures: and the Clicking is unchecked, what keys from the keyboard can I use to check that box?
and in the trackpack options:
the Ignore accidental trackpad input is checked
and
Ignore trackpad when mouse is present is un checked.
I know that there is the problem, the mouse is completely disabled. help please...
thanks

Trackpad Gestures: Clicking

If I use tab and then spacebar, it will go back to the previous and I can do nothing..
The problem is that when I am on the keyboard & Mouse preferences, I type trackpad then it opens but once opened, I can not do anything inside the window like click on the trackpad gestures I have to click on clicking in order to use the mouse...
what is the key to get from the searching (trackpad) to the clicking...
please tell me...