How to recover the Numeric keypad in Ubuntu 10.04

I have a laptop Samsung R540, running Ubuntu 10.04. The numeric keypad stopped working

When you BlockNum key does not work to enable your numeric keypad, try:

1. Try with Shift+BlockNum first.
2. If that doesn't work. Try menu System-> Keyboard.
3. The Keyboard Preferences opens. On the Layout tab, make sure you have a compatible Keyboard model with numeric keypad. If in doubt, any "Generic 105-key" will do.
4. On the Mouse Keys tab, the Pointer can be controlled using keypad option should be unchecked.
5. If the keypad is still not working, go back to the Layouts tab, and click on the "Options..." button.
6. Among the Miscellaneous compatibility options you'll find "Default numeric keypad keys" which should be checked.

HTH.