PowerPC :: Trackpad On IBook G4 Completely Disabled

I have an ibook g4 14" since 2003. It always worked perfectly until now. The trackpad is completely disabled. I cannot 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 unchecked.