The first thing I like to consider is why did the pull cord break? Was it old and frayed and needed replacement? Was the flywheel brake locked up and caused it to break or was the engine or lawn mower blade not turning and it snapped?
You must first understand the why before you can repair the pull cord. Remove the spark plug cable and then inspect the lawn mower blade to ensure it turns freely. It will be a little hard to turn as the flywheel brake is on. If everything turns freely, then most likely the cord was old and needed replaced.
If the engine is locked up and doesn’t turn, make sure there is not a stick or a rock locking up the blade. Engage the safety brake handle and make sure that it is not sticking and not disengaging the brake. If the safety brake is working correctly and there is nothing stopping the blade, then the engine may be seizing up due to low oil.
Put the mower back on the ground and check the oil level. If the level is OK, something internal may have happened to the mowers engine.
But if everything checks out, remove the blower cover and replace the pull cord if you know how to do so. If not, check our Locations page for a lawn mower repair shop near you.