You can replace the recoil starter on a lawn mower that has a flathead engine by following the DIY instructions in this lawn mower repair guide. The recoil starter, which is riveted to the blower housing on top of the engine, has a spring that retracts the starter rope. If the rope doesn't retract, it's likely the recoil spring is broken. Replacing just the spring is difficult; the best way to repair a recoil starter is to replace the assembly using a manufacturer-approved lawn mower part.
Use these steps to replace the recoil starter on common Briggs & Stratton flathead engines that power Craftsman, Toro, MTD, Murray, Husqvarna, Poulan and Snapper walk-behind lawn mowers.
If your lawn mower is a newer model with an overhead valve (OHV) engine, see our repair guide How to Replace a Lawn Mower Recoil Starter on an OHV Engine.