No.

You could recreate an approximation of the original mailmerge main document by replacing the variable content from a representative output letter with the appropriate mergefields and any other fields used in its creation, but that wouldn't resurrect the data source and, without that, you'd have no way of knowing what the correct mergefield names were or, if other fields were used for generating conditional content, what their logic was or, quite possibly, a comprehensive view of all the conditional outputs.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]