When opening a publication (*.pub) in Publisher you may get the following message:
“Publisher had detected a problem in the file you are trying to open. If you are certain that this file came from a trusted source and does not contain harmful information, click OK. If you received this file from another person or machine and are not sure that the contents are safe, click Cancel.”
While the file may be destroyed beyond recognition, you may be able to salvage some of the content from it. To do this, try to insert the file into a new publication using the Insert/Text File command (in Publisher 2010 it’s now called Insert File under the Insert tab).