Starting problems

I have a Mazda B4000 and I am having problems with it starting. About two weeks ago it would not crank, then after a couple of days it cranked again. It has been doing fine for the last week. Now I am driving it more back and forth to my work site and today it will not crank again.
 
I did have it checked out and the mechanic said he didn''t find anything wrong with it. He did say that it needed new plugs and wires because the originals are on there.
 
What on earth could be a cause of this?
 
It won''t crank, then it does and drives for a while, then it won''t crank again.
 
Any help or advice?

Cranking spins the engine, has nothing to do with bad wires or bad plugs (those could prevent the engine from starting providing the starter does spin it at appropriate speed).  So if you have cranking, spinning issue, address that.  First check your battery, battery connections, and your charging system.