This error message may appear in PowerPoint 2010 after other error messages and generally appears when you try to open a PowerPoint file you've downloaded from the internet or in some cases, a network directory.
• Right-click the problem file in Windows Explorer.
• Click Properties on the pop-up menu.
• On the General tab of the Properties dialog box, click "Unblock"
• Click OK.
Note: "Unblock" is at the bottom of the Properties dialog box. If the file isn't blocked, the Unblock button won't be there, so this won't be the solution to the problem.
If you follow these steps, you won't see this message when opening .ppt file. You won't get the protection that this feature offers (though it's debateable whether it offers enough protection to outweigh the aggravation, especially if you have your antivirus and malware protection software up to date.
• Start PowerPoint
• Choose File then Options
• Click "Trust Center" on the left, then click "Trust Center Settings" on the right
• In the Trust Center dialog that opens, click "Protected View" on the left then REMOVE the checkmark next to "Enable protected view for files originating from the internet"
• OK your way back out of all open dialog boxes.
• Try opening the file again.
Also I can suggest this program Recovery Toolbox for PowerPoint https://powerpoint.recoverytoolbox.com/