Maybe some details would help. What kind of document? Where did you get it? What software are you using...etc?
I was using SendNow. I think it happened because the person who sent me the document was just using the free version of the software and so was I, so that it timed out after 7 days. She thought she had downloaded it, but I don't think that's possible. Anyway, when she went back to deal with the changes I had made to the document, it just wasn't there. It was a lot of work that was lost and we were hoping there is some way to find it.
You haven't answered graffiti's questions. I don't know about his, but my crystal ball is not working...
I don't think answering my questions will help anyhow. Doesn't sound like it has anything to do with Adobe Reader.
You may want to go to the SEndnow site and look around for answers there. This would not be the proper forum for help.
Sendnow FAQ's: https://sendnow.acrobat.com/faq.html