Why is it that my vehicle will not start or even want to crank?

I have a 1998 Mercury Tracer LS. Recently when starting, there were moments of hesitation, but eventually the car would start. Now, it does not even want to crank. The battery is two years old. I was told the battery was still good. Nonetheless, I bought a new one. Although the power windows work well as well as does everything to the car, it still does not make even make a clicking noise when turning the key. I have never replaced the starter/cellunoid.