Things You'll Need
Screwdriver or socket wrench
Most push-style lawn mowers use a manual starter, rather than an electrical starter. Manual starters are usually operated by pulling a cord, which turns the starter and cranks the engine. It's not uncommon for these cords to break, leaving you unable to start your lawn mower. Replacing the pull cord on a push lawn mower isn't that difficult, but exercise caution and wear gloves and goggles.
Shut your lawn mower off and wait until the blades stop moving completely before you begin. Examine the starter (usually on top of the mower) to determine whether it's mounted by screws or bolts.
Remove the screws or bolts with a screwdriver or socket wrench. Lift the pull cord starter assembly from the motor and bring it to a flat workspace.
Turn the starter assembly over and remove the center nut. Lift the center cap from the assembly.
Remove any remnants of the old pull cord. In most cases, a small section of the cord will still be inside the starter assembly. Use a pair of pliers to pull it out.
Measure the section of replacement cord to determine where how long it needs to be. Wrap the cord around the assembly two or three times to determine your cut line, and then cut the replacement cord.
Insert the new cord into the designated hole and push it through to the other end. Tie this end of the cord off with a knot to secure it.
Reattach the center cap and tighten the nut. Turn the center cap counterclockwise to begin wrapping the pull cord. Turn it until the spring gives resistance, and then turn it back the other way one full turn.
Insert the other end through the pull cord handle. Tie off the pull cord with a knot to secure it to the handle.
Reinstall the starter assembly and tighten the bolts or screws to secure it. Use the pull cord to start the mower to test it out.
In most cases you can reuse your existing pull cord handle.
If you don't feel comfortable doing this project, bring your lawn mower to a small engine repair shop. Pull cord replacement is relatively inexpensive.
Make sure the replacement cord is the same diameter as the old one, so it will properly wrap around the starter assembly. A larger cord may install correctly but will snap easily because of the extra rubbing it will receive when pulled.