Small Engines (Lawn Mowers, etc.): pull cord wont turn engine over, craftsman lawn mower, briggs stratton

Question
I have a craftsman lawn mower model #917.378491 with a Briggs & Stratton 6.75hp engine model #123k02-0273-e1.  I pulled the starter cord and it came right out.  Went and got a new cord and put it on. The cord pulls out and recoils perfectly, but it does not turn the engine at all.  Any idea what i have done???

Answer
Can you slowly turn the flywheel by hand?  If you cannot remove the spark plug and try rotating the flywheel slowly.  it may be that you hydro locked the engine.  that would come from tipping it and allowing fuel and or oil to run on top of the piston and not let the piston go up and down.  When you pull the starter cord on the new starter is the starter dogs coming out of the inside of starter.  they would engage the cup on the flywheel.  The other thing to check would be the flywheel key remove the starter cup and check they key.  It is the one that attaches the flywheel to the crankshaft.  I hope this helps.