Question: A friend owns a MacBook (13-inch Late 2007), somehow he's managed to screw up all the function keys.

I've managed to reset the ones for dashboard, expose, etc but the play/pause/fast forward/rewind/increase volume/decrease volume don't work.

Any ideas as to what's happened here and how to fix it?

Answer: 
There's a couple of things:

1. Apple Menu -> System Preferences -> Keyboard
2. Untick "Use All F1, F2, etc keys as standard keys"
3. Click "Keyboard Shortcuts"
4. Click "Restore Defaults"

That should fix the problem.

**Edit**:

Some people suggest powering off the MBP, or resetting the SMC completely. Here's a [forum thread](http://discussions.apple.com/thread.jspa?threadID=1775934) which describes a similar situation.

Here's [how to reset the SMC](http://support.apple.com/kb/HT1411) on most recent Apple Portables.

The SMC is responsible for some system IO functions, such as the trackpad, as well as power management functions. It's entirely possible that your keyboard isn't behaving because of this SMC.

Also, does this behavior occur under a new user account? If it does not, I would be inclined to trash any files from the first user's library related to keyboard - or simply migrate to the new user account, whichever is easier.
You can use the utility [FunctionFlip](http://kevingessner.com/software/functionflip/) to change the keys from Fn keys to special features. Maybe that can help fix the problem.