Touchpad on my laptop works, but not the hard mouse keys

[zabadabadoo]

@sparrowbread

It's the mouse built into the laptop

So you are actually talking about the laptop's Touchpad, not a mouse.
If you can determine the maker of the Touchpad e.g. synaptics, then maybe something in this thread could help you:

Touchpad doesn't work

Do you have touchpad synaptics installed? sudo apt install xserver-xorg-input-synaptics