US citizen applying for OCI card but do not have indian passport

[varpra]

We applied for OCI card with all the supporting documents. Since we do not have Indian passport with us anymore we submitted other forms of identification (birth certificate and high school certificate). The application was returned back to us asking for photocopies of the first pages of the Indian passport. Indian passports were either submitted at the time of getting the US citizenship or at the time of getting the US passport. This was done long time ago. We do not have the Indian passports with us anymore. What do we do apply for OCI card? Whom do you approach to get an answer of what documents can be submitted in-lieu of the old Indian passport?. I checked some threads here and found the link for this renunciation of Indian citizenship document
/indian-citizenship-renunciation-certificate/
but no help. Is anybody in this situation?, if so what did you do to get OCI card?