Chuck, My oldest just did this about a year ago. She was born at Kef, and her ex lost the original state dept birth certificate. Here is the link: https://travel.state.gov/content/travel/en/international-travel/while-abroad/birth-abroad/replace-amend-CRBA.html
Chuck I has same situation when my daughter was born in Barbados in 1969 and had a State Department birth certificate issued at that time. I would contact State Department as a start. EKD
Chuck,
I had two daughters born in Barbados 1963 & 1964 and when I transferred to SNI in 65 I went to San Francisco and had them both naturalized. At that time they (Naturalization people)were mostly interested in the original hand written birth certificates (that I had) from Barbados. They stated at that time that the Government proof of birth abroad was merely a starting point to track down the original birth certificates needed for naturalization (which they required at that time)etc. Not sure what they would want now. Good Luck, Ed Smock