Engine will not turn over - 2005 Chevrolet Colorado

Engine will not turn over.first check battery volts, should be 12.6 volts. if not battery is weak or dead make sure battery cables tight and clean them if you see a lot of corrossion use baking soda and water neutralize corrossion remove battery cables clean them with wire brush also clean battery post terminal with wire brush also wear safety glasses protect your eyes now.try charging and jump start vechicle see if battery good or starter at fault bench test starter and starter solenoid if starter dont work problem in the starter.if starter good.you have blown starter fuse bad starter relay if dash lights dont light up when you turn on the ignition switch and battery has 12.6 volts.check ignition fuse if fuse is good dash still dont light up,you could have faulty ignition switch.if all is good you could have bad clutch safety switch for manual transmission or faulty neutral switch for automatic transmission.if you have the late model cars from 1996 to 2012 has the theft security system which will cause car not to start and try turning engine over with a large wrench to make sure engine not locked up.