Use mouse without mouse. Use keyboard to operate mouse.

Yes this is a good trick and thing for those who have some mouse problem and no mouse.
1)Press Left Alt + Left Shift + Num Lock Button
2)Click OK.
3) Now with the numpad you can operate your mouse.

7 8 9

4 6

1 2 3

For normal click press 5.
4) To again revert to default settings just press the above key combination again.