Try resetting resetting the PMU?
If that doesn't work, then it sounds to me like a faulty keyboard.
You will require a replacement. They are easy to replace and cheap to buy on places like eBay.
replacing them is a simple pull out plug situated under the RAM slot under the keyboard. depending on what model of iBook you have.
http://www.ifixit.com/Device/iBook has guides on how to fix parts like keyboards.
it's simple enough to do yourself.
Best of luck
The keyboard is a wearing part. The circuit path connection between several keys of your keyboard broke. Try to get a used keyboard on ebay or from other sellers for your iBook model. There are G3 and G4 iBooks and 12" or 14" models so you have to pick the right one - some keyboards are interchangeable between different models .