MISSING E BOOK ON ADOBE DIGITAL EDITION 4.5

Good day

I have downloaded two books,  for study puproses, had it on my laptop, used the one, when wanting to open the second book,

the it was just a cover and the word missing.  I have downloaded multiple copies on my laptop, but don't know how to open my books from my laptop with Adobe digital edition, and it is not found on the app itself.

I thought by deleting the "missing books" I would be able to reopen it from my laptop, now I cant even find the deleted items,

Please assist.  

Thank you