To open PowerPoint 2007 files in older versions of PowerPoint you need to download and install a compatibility addon for your PowerPoint. The old versions of PowerPoint would save files with .ppt endings while PowerPoint 2007 saves files with .pptx endings.
Download and install thisPowerPoint addon to be able to open the .pptx files with the older PowerPoint versions.
Thanks for this great Support Dear Team….Love you all….Best Wishes Microsott !