If you get an error message saying that, "Sorry, PowerPoint can't read" your file, try these procedures.
The simpler solution is to unblock the security measure that prevents the file from being opened.
Unblock the file
In File Explorer, navigate to the directory that contains the file you want to open. Right-click the file and choose the Properties command.
In the Properties dialog box, on the General tab, click the Unblock button.
Click OK to close the dialog box, and attempt to open the presentation file again.
Another possibility is that the file has been corrupted. PowerPoint may be able to repair the file and open it.
Repair the presentation
In PowerPoint, choose File and then choose Open.
Browse in the Open dialog box to the directory that contains the file you want to open.
Select the file. Instead of clicking the Open button, choose the downward pointing arrow next to it, and then choose the Open and Repair command.
PowerPoint will attempt to repair the file.
If these steps do not solve the problem for you, please leave a comment at the end of this article by answering the Was this information helpful questions. Including details about your experience (such as where the problematic file is located—on your computer, on a network, in cloud storage?) will help us improve this article.