MacBook Pro users are all too familiar with a trackpad that doesn't click properly. Sometimes it just wears out. Before you do an expensive repair, check your MacBook's battery for bulging.
Photo by Charles Williams
MacIssues lists a bunch of reasons your trackpad may stop working. Believe it or not, it may be the battery. Batteries often bulge as they get older, and since the battery is located right under the trackpad on some models, that bulge pushes against the trackpad.
All you need to do is remove the battery, plug the laptop into the wall, and see if the issue persists. Places like Other World Computing sell batteries and show you how to remove them. Check out the link for other reasons why your trackpad could be failing.