Depends When your trying to turn it over the starter doesnt click? If it doesnt take a test light an see if its getting power on the Big wire on the starter Should be constent power with switch on or off, and the small wire it should get power when you try an crank it, if it does then take a hammer an lighty tap the starter while trying to crank it and if it turns over or trys the start is bad, if its getting power it should turn over an the starter can still be bad even if your trying to hit it with a hammer...
if its not getting power then it could be your ignition switch, or alarm you can look under the dash an there should be atleast 2 inline fuses by taking all the fuses out of the alarm it will bypass it an should crank try these an let me know if I can help