Usually the city or county registrar can get you a certified copy.
By that I mean, they go down into the archives and find the book. If the person knows where they were born, a hospital might have those records...but that would be a stretch.
Finally if there are other supporting docs a judge may have to declare you born.
“Usually the city or county registrar can get you a certified copy.”........
TRUE STORY:....An AMERICAN BORN citizen, my Grandfather moved to Canada during first world war, joined Canadian Army which hen made him a Canadian citizen. After WWI, attempted to return to U.S. Needed a birth certificate from city of birth (Lake Linden, Michigan) only to find local court house had burned down destroying all records. Then, still a Canadian citizen, moved back to America and filed a “Green Card” every year until his death back in 1960. He was in his high 80’s at time of death. I personally took him to file that green card. Make sure YOU or a relative obtains and keeps a copy (secured) of you birth certificate.
My Dad was born in 1925 and has no birth certificate even though his younger and older siblings do. DNA tests prove they were siblings.