I have a lawn mower I need to replace the cord attached to the handle.

At one time a big percentage of starter cord rewinders were pretty much the same design, but some variations have acquired significant market share. The trick is learning how to get the recoil starter off the engine without accidentally opening the rewind spring enclosure. Once loose the springs can be tricky to reassemble (been there, fortunately the scars have faded).

The older design is on top of the engine centered over the flywheel. One popular engine manufacturer designed a line of mower engines with the starter recoil mechanism on the side of the engine, which engages the edge of the flywheel with a gear. The misleading aspect of that design is the way the cord comes out of a funnel like opening in the plastic housing that encloses the flywheel and fuel tank.

You should repost with any make and model number information you can obtain from the labels on the engine and the mower itself.

There is a sticky in the beginning of this section that addresses repairing a cord.

I have a lawn mower I need to replace the cord attached to the handle.
Thanks I fixed it