Bear in mind that for some types of Lycoming starter motors, if you have tried to start electrically, and run the battery flat doing that, the starter pinion often remains engaged to the ring gear, and this will make hand propping the engine extremely difficult.You'll know if you try!
On the other hand, for Continentals, if you have had a starter drive failure (as opposed to simple flat battery), and the starter won't start the engine because of that, THE ENGINE SHOULD NOT BE STARTED! The starter drive must be replaced first, or it is likely it will fill the engine with metal from the damaged drive.