how to reset my mac book without cd

Please note: there is no such thing as a MacBook Gr4.

And, there is no such thing as a MacBook G4, as all MacBooks have Intel processors.

Also, are you asking about reinstalling the operating system? Perhaps you should explain the problem you are having that makes you want to reset.

Get more information about your computer. Go to the Apple in the upper left corner of any window, then "About This Mac". Write down what it says about "version"and report that here. Now continue to "More Info..." Copy and paste the information here, but omit the serial number and Hardware UUID (if present).