Hello, a couple of weeks ago, I downloaded a PDF file from my tablet, and began to read,( I found it very interesting) but suddenly some days ago I tried to open it, and poped up a window with the following: "There was an error opening this document. The file is damaged and could not be repaired." I copy the file to my laptop but it didn't work. I do not what happened. Is it possible to repair it? Thank for help.