I have lost magic mouse2 & keyboard Thanks as above I think I have to uninstall and re-install both but theyare undiscoverable as well. . Am I on right track? I'm nogeek also could not find library anywhere. Appreciate help have been at this for hours. Thanks am writing with apple onscreen keyboard and USB mouse.
once the mouse and keyboard are close to your computer and turned on, go to the System Preferences and click on either the mouse or keyboard options. Both of these panels have a buttom in bottom right which says Setup Bluetooth Mouse or Keyboard. The panes are shown below.



And for the keyboard.



Use these to setup your bluetooth devices.