I have a macbook pro and F3 for launchpad and I tried to restore it and its not working. Help please, what should I do?

Not sure what you are asking here.

Are you saying that pressing F3 no longer brings up Launchpad?

If so check System Preferences > Keyboard > Keyboard Shortcuts

Follow the instructions at the top of the box. (Double-click "Show Launchpad" and then press the F3 key on your keyboard.)

Should start working again.

Also, make sure that System Preferences > Keyboard > Keyboard "Use All F1, F2, etc, keys as standard function keys" is UNchecked.

Hmm you're right. It won't let me assign that modifier either.

Strange. Sorry that didn't work.

I wonder if pressing the Restore Defaults button on the same screen would restore you defaults and allow the key to start working.

How old is your Macbook Pro? Does the F4 key look like a circle with a dial and a pointer?