You are working in your pc and suddenly your mouse has stopped working. In that case you can use your keyboard if you know the short cut keys. What is the condition if you does not know the short cut keys. You can now use your keyboard similar to your mouse! Isn't it amazing!
Now press "left alt+left shift+numlock" at the same time then, a dialog box will appear on the screen. Click ok in that dialog box. Now your keyboard has become a mouse. You can use number 5 in the number keypad for the click option and the remaining keys for the movement of the cursor.