Mt ryobi pull cord shreaded and part of it is in the weed eater how do i replace

Go to following site http://hcpi.arinet.com/scripts/EmpartSAPI.dll?MF
Then type in your model no.
Do not know your model no. but normally you have to remove the shaft. First remove the throttle cable from carb. and disconnect the switch wires from shaft. Then pull shaft out of motor housing. There should then be a couple of screws in the shaft housing, remove them. You will then have to remove the clutch and drum, notice if there is an arrow on the clutch to show which way to remove. Use a brass or copper bar to strike the clutch to loosen in direction shown. If you have compressed air and an impact that would be a better choice. Now remove the four screws holding the starter housing and you should be at the starter rope.