I spent most of yesterday working on a PPT presentation. When I printed it, PPT crashed, and now when I try to open the PPT file (technically the .pptx file), I'm told "PowerPoint cannot open the file [filename] because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file." So apparently when PPT crashed, it corrupted the file. I figured I should be okay, because I have PPT configured to create autorecover information every 15 minutes, and I also have it configured to keep the last autosaved version if I close without saving. But going to the directory specified for autorecover files shows only a file named PPT14.pcb, and it's from several days ago. Then I figured that maybe the autorecover files had been somehow deleted when PPT crashed, but I should be able to recover them from the cloud, because I run online backup software that backs up all modified files every 15 minutes. But there is nothing newer in the cloud archive than is present in the autorecover folder. At this point, I'm out several hours work, despite having configured PPT to save things ever 15 minutes. I must be missing something. Can somebody please explain how I can get back a recent version of my PPT file, i.e., the most recent version available before the program crashed and corrupted my primary file?