G4 has keys that will not work and prevents me from signing in.

E-bay is the best source of used iBook parts. You can usually find reasonably priced items.

Is the computer an iBook G4 (white powerPC) or is it a MacBook (white Intel)

since you have a mixed name for the product you have issue with...

The keyboard on an iBook G4 12 or 14-inch model is easier to replace than

that of any MacBook model, so be sure to inquire with correct details when

you choose to search for a replacement part. PowerBookmedic may have a

used working replacement for iBook G4. Note differences in 12"/14" iBook G4.

An iFixit guide may be of help, too. You can go to ifixit.com and look at Mac

portable guides and choose the correct one for your computer build model.

In the meantime, see if you can use a USB wired keyboard, even one from

a Windows (ugh) computer can work. Some of the keys do different things in

Windows than with Mac OS X. Here's an information page from MS about it:

•Keyboard mappings using a PC keyboard on a Macintosh:

https://support.microsoft.com/en-us/kb/970299

Good luck & happy computing! 🙂