Unknown file format after upgrading iOS

[tpayne094]

Hi.
I have upgraded iOS to 10.3.3. version on Iphone 7. But after upgrading i cannot open one very important PPTX extension file which was emailed to me a month ago.
Getting a message saying 'Unknown file format'. I could open this file before.

Any thoughts please?
Thanks

 

[oliver555]

You need to have Office Mobile apps for iOS, which contains Word, Excel and PowerPoint. Details are available at the Office News web site .
Also you can find info here how to recover pptx file http://www.pptx.repair/