I have been to India before, but have since renewed my passport so have no record of previous visa details. What does one do about completing this question online? I am French and we are not allowed to keep old passports.
Contrary to what honorable @uncovery suggested, I wouldn't recommend stating that you haven't been there. Ethics aside, India scrutinizes visa applications carefully (they seem to be afraid of people of Pakistani origin), so your incorrect information is likely to be uncovered.
Note that Indian visa application form asks for a lot of information which is not going to change (for example, your parents names and places of birth), so it is quite easy for them to match you in a computer.
What I suggest to do is to:
- State correctly that you have been issued a visa before, and been to India.
- State "Yes. See attachment 1" in "Have you ever visited India?" question.
- Add a document titled "Attachment 1" where you explain that your previous passport with Indian visa and travel details is not returned to you, and thus you do not have those details. State the year where you been issued a visa, and a year when you visit, if you remember. This should be enough.