97 Cutlass wont start

Battery and starter/solenoid are good. Car makes click sound which I believe is the starter bendix drive sliding into place. A friend suggested that it may be hydrolocked and I should remove spark plugs and try to start the car. I took out the front 3 and tried to crank the engine. Nothing happened but the click noise. Someone else said that I should try to turn the crankshaft by hand with a wrench and breaker bar. I tried to turn the crankshaft clockwise (as I am facing the front with the pulleys and serpentine belt) and I could not turn it. The wrench broke. It will turn counterclockwise with little effort and I turned it only about 1/8 turn. Any ideas? Is there a sensor stopping the crankshaft from turning? BTW, the car was running very well when I parked it. The next morning it would not start.