Possible things to check out.
Check the cables connected to the battery to make sure there is a solid connection, a poor connection will not allow enough power to the starter. After that, I would check the fuse box to make sure the starter fuse is not blown, if that was fine. I would take the starter out and have it tested at your local autoparts store (if you havent already). Kragen, Autozone, Oreily, etc... check them for free.
Other possible problems causing engine not to turn over: bad starter solenoid, broken ignition switch, broken timing chain, bad ignition coil, dead electronic control module
Here is a training manual, it might help: http://www.prestolite.com/pgs_training/t...