It could just be a bad connection or faulty battery cable. Here are a few things you can test to figure it out. First off, these tests assume that the "click" you are hearing is coming from the starter itself. If not, you could have a problem with a relay, factory alarm system or neutral safety switch. These problems are too difficult for me to tell you how to diagnose, so you will need a professional. If the starter is your click, proceed as follows: You will need a voltmeter. A Digital meter is best, and if you don't have one you can get one quite cheap at many auto parts stores.
First, put the voltmeter leads on the battery in the center of the posts and have someone try to start the car. Note the voltage. If it is below 10 volts while trying to start, you have a bad battery. If not ..
Next, put ONE of the voltmeter leads in the center of the negative post (not on the cable - the actual battery post), the other on a metal surface of the engine, preferably the body of the starter itself. This can be a bit physical, so be careful to raise and support the vehicle properly, and not put your limbs in harm's way. Have someone try to crank it again. Note the voltage. A cheap meter will probably say something like .1 volts or somewhere close. This is good. If it reads more than 1 full volt, the cable or connection to the battery is bad. This is called a voltage drop test.
If the above tested good, place one voltmeter lead in the center of the positive post, the other on the positive terminal of the starter itself. Again - watch your fingers! Have someone try to crank again, and you may need a third person to watch the meter if you are under the car holding the lead to the terminal. Once again, you want to see less than a volt. If you have more, that's your bad connection.
Hopefully this found your problem. If not, it's probably time to bring in a professional.
I hope this was helpful to you. At my shop, probably 1 in 5 "no crank" problems is a bad connection or cable, so it's important not to overlook it.
