Take a look at Speedy Jim's website here under "Why won't my engine start", then come back with more info.
This happened to me last year and the whack with a hammer did the trickjoebo said:sounds like the starter motor , get someone to turn the key while you look underneath (make sure its not in gear ) if the starter motor clicks then the solenoids ok and it maybe just jammed , twat it with a hammer while someone turns the key, again make sure its not in gear and handbrakes on ,