As Jonny said, you can go to your ward office and get your birth certificate from there. They have standard format which has English and Nepali version in same paper. I did in KTM so not sure if it is same for other places. One of my friend had hand written letter from VDC secretary and he said that worked for him as well (he translated and notarized from notary office in KTM I guess).

Also, once I got my birth certificate, I attested the documents by sending it to Nepalese embassy in DC (Keep in mind they might take >3 weeks to send you back your documents)

Good luck