I am sending you some instructions for replacing a pull cord on a Craftsman trimmer. Without a model number, I might describe some parts that your trimmer doesn't have. If this happens, ignore the part that does not apply to your trimmer.
Remove the trigger housing on the drive shaft by removing the 4 screws and separating the housing. Make note of how the trigger and the throttle cable mount in the housing.
Remove the clamp on the clutch cover and remove the drive shaft and housing from the clutch. (it pulls out).
Remove the screws from the clutch cover and remove the cover.
To remove the clutch drum, remove the small torx head bolt in the center of the drum. The clutch drum will slide off the engine shaft. If the engine shaft turns when you are removing the screw, remove the spark plug and fill the cylinder with small clean rope. The rope will jam the piston and stop the engine from turning.
Remove the screws holding the fan housing to the engine and remove the fan housing. The rope and the starter pulley are inside the fan housing.
Be very careful removing the starter pulley and spring. The spring will unwind violently if it is released.
As you install the rope on the pulley, turn the pulley. Let the turning of the pulley wind the rope and it will load the spring so it will retract.