How are you attempting to turn the engine over? What are you calling the starter flywheel? You can usually rotate the engine with a socked and a breaker bar on the big nut at the front of the engine on the crankshaft. It's not real easy but will show the engine is not frozen. If you mean the starter won't turn the engine that can be as simple as a weak or dead battery or dirty connectors at the battery. Please elaborate on the problem. More info may yield a solution.