Question

who had dug the well where was it dug

Answer 1

We had not dug the well. Where was it dug ?

Explanation:

Who had dug the well where was it dug ?

This sentence belongs to the past perfect tense as the formula of past perfect  sentence is

Subject + had + third form of verb + Object

To make it negative not is used after had such as

We had not dug the well where was it dug ?

Had we dug the well ? Where was it dug?