Its better if you can make a birth certificate from the place your passport/ citizenship was granted...
 
Having said that, do not attepmt to make a fake one...cuz I am sure you're going for Interview shortly with NVC for your Change of Status
& they specifically ask & look at your Birth certificate....My suggestion would be:

Go to the place you were born ...either municapality or VDC in nepal & try to convince one of their representative about the requirements mentioning your relationship with your parents, because one of your parents ...either your mom or dad must be origionally from the place you were born n they will make one out for you

Once you get that certificate, in my case i got one in english.....nevertheless, go to Distict Development place & Notarize it....that way you gonna have both form in clear & concise manner !!!

Good Luck

Sources: Been there n done that !!!