MacBook Pro TrackPad Butttons Stopped Responding

My MacBook Pro 17" Trackpad button stopped working. I use my laptop everyday and usually have a wireless mac mouse connected but when I wanted to use the laptop by itself the trackpad button stopped working. Any ideas on how to check it? Apple is calling in the morning but wanted to get some work done done. Any hints will be appreciated tremendously.

Just a note: the keypad and the actual keypad work fine.

If it's a failure of the button mechanism itself, you'll likely need to have it serviced. But in the meantime, I would enable tap-to-click (and two finger tapping for right-click, if you don't already have it turned on). This way you can just tap the trackpad itself for a click.