1999 Isuzu Trooper Car won't start

I was on a trip in my trooper. It drives great. I started to notice when I was starting the vehicle it was beginning to lag before it started, but it would always start. then when we stopped the car to fill up gas, it really had a hard time starting, and almost sounded like it would not go but it did, and I had a feeling that it would be the last time it would start. I was right, when we got where we were going it would not start again, yet it drove beautifully the whole time. The battery seems fine, all the electrical things are still working, but doesn't even make any sound when I turn over the engine?????