Q: Trackpad button is stuck

Keep in mind that the top 3/4" does not press or much anything else>

Also read thru these:

http://support.apple.com/kb/TS1248

http://support.apple.com/kb/TS1449

You can also try a SMC reset:

http://support.apple.com/kb/HT3964

Follow directions for a battery you should not remove yourself.

There is one other thing to aware of, some batteries become swollen (they are under the track pad) and have been known to cause problems, espcially clicking. If left unattended to they can create more problems. You should have this checked at an Apple genius bar (make an appointment)  the disgnostic is free.