Can a "Destroyed" Helicopter be repaired and flown?
The NTSB defines Destroyed as 


  Damaged due to impact, fire, or in-flight failures to an extent not economically repairable.


Another common definition is: 


  The estimated or likely cost of repairs would have exceeded 50
  percent of the new value of the airplane had it still been in
  production at the time of the accident.


This fact that the costs of repairing are estimated to be exceed the economical value of the aircraft does technically not prevent the aircraft to be repaired and made flyable again. It can be recertified on the original airworthiness certificate. See FAA order 8130.2H. 
Special attention needs to be given to the identification plate (serial numbers etc.) of the aircraft; the original plates of the aircraft have to be installed.

Do not expect any support from Bell as on their website they state:


  There are some aircraft that have been destroyed in an accident or
  retired from service that are no longer considered to be genuine Bell
  Helicopter Aircraft. These aircraft will not be supported by Bell
  Helicopter.


This makes resurrected Bell helicopters very difficult to sell in the future.