The starter relay is at the right rear of the engine compartment. You can check for any voltage drops with a multi meter to see if the relay is bad. I would also make sure the ground is good for the battery . I have seen intermittent cranks caused by loose battery grounds.
let me know what you find
Ok what should the voltage reading be? and should the key be in the on position when checking?
I would try to start it (you will need some help)and the voltage should be or very close to battery voltage. We should see no more than .5 volt drop.
sometimes giving it a rap will restore contacts enough to start again.