Problem with Comments on my site

When I upgraded my site from Drupal version 6 to 7, something happened that caused some comments to go haywire. As this was many months ago, I do not have any backups. Unfortunately, I had to delete the comments.

Somehow, the body of some comments was removed from the field_data_comment_body table. Interestingly, the author and subject information was not deleted - it is stored in another table.