Apple - Macbook Pro TrackPad not clicking

This video recommends resetting the SMC:

1. Turn off your computer.
2. Plug in the MagSafe adapter.
3. Press Shift-Option-Control, on the left side of the keyboard, and the power button, at the same time and hold it for 5 seconds.
4. Let go of all the buttons.
5. Turn your computer back on with the power button.

For more information on the SMC reset see this Apple support article

Sometimes its just your magic mouse is sitting somewhere, maybe in your bag and triggering a click. Make sure you turn off the bluetooth.

Depending on your macbook pro model you should see a small screw on it inside the computer. Just do 1/4 turn left or right to adjust click on the trackpad