Cranked kinda slow-then next time Nothing.

The vehicle ran fine. Then yesterday I went to leave and noticed that it seemed to crank a little slow. I didn't think much of it because I had actually reached around the steering wheel from standing outside the driver seat to crank it. Ran fine all the way to the store and idling while inside. But I turned it off at my 2nd stop and when I got in about 30 minutes later to leave—NOTHING. All lights and radio was fine, it just wouldn't make a sound when I turned the key forward. Not even a click that was very noticeable if at all.