If the fall rope of the treadmill is lost, you can take the following measures to deal with it:

1. Stop using the treadmill. Turn off the power to avoid any accidental injury.

2. Contact the seller who bought the treadmill and buy a new emergency stop safety rope.

3. If you can't buy a new safety rope, you can try to use a magnetic hook instead. Suck the magnetic hook on the magnetic switch of the treadmill, and then tie the rope when the treadmill stops in an emergency.

Please note that the above measures are only temporary measures, and buying a new safety rope and installing it correctly is still the best practice to ensure the safe use of the treadmill.