My children were adopted by my sister,my sister died and I want a copy of my children's birth records with my name on it. And vital records in my town said the only birth certificate I can have is the one with my sister's last name.can I receive a copy of my children's birth record from the hospital's they were born at?and is the hospital liable for saying (the company they used to store my records)went out of business and they no longer have the record of my daughter's, birth. What can I do or should I do?

You are legally not their mother.

There IS no legal birth certificate showing you as the mother.

While there may be medical records that you can request for YOURSELF that state that you gave birth--you have NO RIGHT to the birth records of your sister's children.