If you're having problems with the buttons on your PS3 controller, you may be thinking about tossing the controller out and just buying a new one. That is one option, but you ought to consider attempting to fix it first. Even if you don't know much about electronics, you'll find you can open up the controller, diagnose the problem and fix the buttons without too much trouble.
Unplug your PS3 controller from the port in the front of the console and place it face-down on a table or desk.
Use your Phillips screwdriver to remove the five screws located on the back of the controller and set them aside. Lift the back half of the controller from the front to expose the battery and green circuit board underneath.
Lift the battery up and inspect the connector wires to see if they are securely plugged into the battery port. If the problem is with the buttons rather than the battery, proceed to Step 4.
Lift the battery up, unplug the connector wires and set the battery aside.
Lift the circuit board out of the housing to expose the backs of the actual buttons.
Lift the rubber pads off the backs of the buttons, then make sure each individual button is fitted securely in its compartment. If any are loose or aren't fitted properly, simply lift them out of the controller and refit them. Then reassemble your controller in the reverse order you took it apart.