I have a file that was only stored on a thumb drive (no backup). I removed the drive and opened the file on a different PC, amended it and saved it. When I went back to my personal computer, it says that the file is corrupted. I think I just removed the drive without ejecting it. All other files on the drive are fine. I went back to the other PC as well but it also says it is corrupted. It is an .xlsx file. Help. The file has probably 15 tabs in use.