I have had a chain put in my mouth to pull a tooth down and the rope thats attached to my gum has come away so my chain is dangling down! What do I do?

Chain. You pick up the phone and immediately call your treating General Dentist or Orthodontic specialist. If attachment area closes over it will have to be reed posed. Don't wait, call now.
Call your dentist. The chain will need to be re-attached.
See the orthodontist. go and see your orthodontist so they can rectify the problem - such an issue may slow and or cease the moevement of teeth we wish to see.