My question involves name change laws in the State of: Va

My last name on my birth certificate has my mother's maiden name, and when I started school my Mom put down her married name down to register me in which she was married a month after my birth to my Father. The school over 40 years ago never asked for a birth certificate, just allowed my Mom to register me into school under her last name. I have always used her married name as my last name all of my life, and when I got married then divorced 4 years ago got a court order to change my name back to the name that I have always used. My question is how do I now change my last name on my birth certificate to match the last name that I have used all my life? I would like to apply for a passport and know I will run into a problem because my birth certificate shows another last name or my Mom's maiden name. Do I just do a name change form for Va and send in a certified copy of the last name change from changing my name back from my divorce? Please help!!!