@Tommym42 If it's just the rope, go to any small motor repair shop and get about 30 inches of 1/8" starter rope. Take a piece of your old stuff with you, just to make sure you get the closest size they have.
You can also order one from DDM:
http://www.davesmotors.com/DDM-Replacement-Pull-Start-Rope-for-R-C-Engines-146159.html But you should easily find some locally for less than $2.
Learn how to tie a stopper knot first:
Next, use this video for installing the rope:
All the other methods require tearing down the pullstart, which is just unnecessary. Ignore the tech BS for the cable. Just pull your rope through and set your stopper knot and follow the rest of the instructions. You should be up and running within minutes!