Missing the mouse

To connect a wireless mouse using only a wired keyboard on a Mac, use keyboard shortcuts to navigate to the Bluetooth settings and pair the mouse.

Open System Settings: Press Command + Spacebar to open Spotlight Search, type Bluetooth, and press Return.

Enable Full Keyboard Access: If the Tab key doesn't move through the menu, press Control + F7 (or Control + Fn + F7) to enable Full Keyboard Access.

Select your Mouse: Press the Tab key until the "Devices" list or your wireless mouse is highlighted. Turn your wireless mouse off and back on to trigger pairing mode.

Connect: When your mouse appears on the screen, press Tab to focus on it, and press the Spacebar to connect.

If the mouse is connected to another Mac, that Mac must be shutdown or made to forget the mouse before other Mac can Connect to it, also turn the Mouse OFF/ON.

If your mouse no longer appears in System Settings >> Bluetooth, first turn it off and back on and make sure Bluetooth is enabled.

If it’s an Apple Magic Mouse, connect it to your Mac with its charging cable, wait about a minute, then disconnect it.

Apple says this should pair the mouse automatically. (Apple Support)

If it still doesn’t appear, restart the Mac and try Bluetooth again.

For a non-Apple mouse, make sure it is switched on and in pairing/discoverable mode before checking System Settings >> Bluetooth >> Nearby Devices. (Apple Support)

Apple’s relevant instructions are If you can't connect your Magic Mouse to your Mac and Connect a Bluetooth device with your Mac.

Is this mouse a USB or Bluetooth mouse? If it's a Bluetooth mouse, you will need to forget the device in Bluetooth settings and initiate the pairing process again; this process may vary depending on your mouse vendor. If you're using a USB mouse, ensure it's plugged in or unplug it to plug it back in again.

There are also mouse settings, you won't see them if there isn't a mouse paired or plugged in. On MacBooks it will show as "Trackpad" Settings, under "Keyboard."