You caused the oil leak by tilting it up with the carburetor side down, which you should never do. Sometimes oil is sucked into the cylinder and results in a hydraulic lock. Take the spark plug and air filter out. If it's a pleated-paper filter, you'll need to get a new one if the mower can be used again. Pull the starter cord with the plug out to get a feel for the severity of the problem and to clear the oil from the combustion chamber. Now you can tilt it up with the carb side high to check for a bent crankshaft. Spin the blade to see if the blade bolt head seems to describe a small circle rather than just turning in place. The other problem usually resulting from an accident like this is the flywheel probably sheared off the key and tuned on the shaft. You'll most likely have to reset the flywheel before it will run. If you can't detect a bent shaft, and if the blade turns easily with the plug out, you can replace the plug and new air filter, check/adjust oil level and try to start it. If it kicks back and backfires, etc., you'll have to reset the flywheel with a new 'Woodruff key'.

Pull off the recoil mechanism, pull off the flywheel/fan retaining nut. See if the key is sheared.

Coho, By your comments one would think you have an electric PTO clutch. I looked at the Sears number and you've got a manual engagement system. When the blade engagement lever is brought down, the tension on the blade belt is taken off, and blades should stop...QUICKLY. There are blade brake stops on the belt pulleys that assist with this. Either your blade brakes are worn, or you have a blade belt on this mower which is TOO SHORT and not taking enough tension off the blade belt to stop the blades. Bear in mind...if engine's still running the engine pulley on the crankshaft is STILL TURNING so....the belt's still receiving input from there. If the mower's still performing well (with or without a correct belt), the ONLY SAFE WAY to empty the bag, clean chute, etc...is to stop the engine. Check the blade braking system, and replace the belt with the correct one. Most likely...will be the blade brakes are worn out. You'll need part# 131845 to replace this with. There's one on each belt pulley. Worn brake pads are pretty common on these machines and unless they're maintaining a "hold" on the belt pulleys, the belt will want to continue to spin the blades. T-Man

It would help if you provided name of tractor, the model, the serial number. It's like saying, "my fan belt broke on my car, where do I find belts.?"