If you've arrived at this article because you got an error message that PowerPoint can't read a file or that the presentation cannot be opened, it's likely that Office has blocked the file for security reasons. You can unblock the file so it can be opened:
Open Windows File Explorer (Open Start in Windows and type File Explorer.)
Locate the problematic file on your computer.
Right-click the file and select Properties.
In the Properties dialog box, look for an Unblock button near the bottom right. If it exists, click Unblock, then click Apply, and then click OK to dismiss the dialog box.
Now, attempt to open the presentation again. Right-click the file in File Explorer and select Open.
Still having trouble?
If you're having a problem with PowerPoint that's not resolved here, please contact us for technical support.
For a discussion about why Office blocks files, read Block or unblock external content in Office documents.