Ediscovery software, and I used a bespoke solution in that job, takes a job that can take weeks or months the and makes it possible to do it in days. Or y'know, you could use a filing system and do it in minutes?
Sometimes unfortunately you have no idea of the keywords to search for...
... or you drown under the ocean of unrelated finds, which is my usual experience with mass-applied windows indexing (in the form of massive corporate sharepoint)