Retrieving old E-book following hard drive crash

At the end of 2017 the hard drive of my computer crashed that the data was eventually retrieved at the beginning of 2018.

I had one E-book on "Adobe Digital Editions" at the time which I think I bought in 2016. I had not looked at it regularly.

I bought a further book in 2018 which I can access through the software installed on my new hard drive. I have now actually discovered the previous book which is on a backup drive and I have tried to retrieve and display this book using the software. However, it will not reload claiming that the "vendor account is not associated with the item I am trying to open"

What does that mean!!

I don't think I have any records as to the organisation from whom I bought this e-book back in 2016.