Sorry for not being more specific. The switching on of the Mouse Keys actually changes the function of the keys on your numeric keypad on your keyboard to emulate what the mouse does.
You can still use the mouse too, it doesn't disable it, or you can use both the keyboard and the mouse. Click on the link in my previous post for more information.
It can take a while to get used to using the mouse keys, a little like learning to ride a bicycle that steers left when you turn right, lol, but you'll get the hang of it if you persevere.
↓↓ EDIT : You're very welcome PB, thank you. ↓↓