Urgent "perzi desktop says that my file corrupted or damaged"

Dear ,

kindly be informed that i canot open my presentation i have made before traial period ends and after it ended when i try to open for view only my .pez doesnot open it keeps saying loading forever , i reinstalled the newest prezi for desktop and now it gave me message " file is invalid or damaged " please help me i need my presentation ASAP and i have worked on it for a long time