Truck wont start and can not figure out what is wrong?

I drive a 2002 Chevrolet s10 4.3L. Just about a year ago I drove up to my moms work fine and when i tried to go home my truck would not start and we had to get it towed home. Then later that night the truck started.. Now it wont start again. My dad just bought a new battery today thinking that was the problem, but it still wont work. The truck will turn over, just not start? Does anyone know what is wrong with it? My dad said something about a fuel pump but he isn't sure