Help no crank no start.

I need some help guys. My car was fine then I went to autozone to return a tool then I came back to the car and it won't start! It won't crank or anything just one click sound when I try to start. Had them bring out a new battery and still same issue so not battery problem. I did notice my car started to idle up and down a lot when I first turned on the ac but not sure if that is related. Any ideas? Tried jumping and it doesn't help.