cant open saved files on ipad also screenshots

I’ll try to explain what might be going on…

If using the in-App file browser within Apple’s native Pages, Numbers and Keynote Apps, only the files relating to that App are directly accessible; other files within the filesystem are visible - but are deliberately shown with Grey file icons; this indicates that the file-type cannot be opened from within the current “active” App. 

If you wish to edit, move or delete any of the files with grey icons, then you should use the Files App - which allows access to all files within the filesystem.  Note that photos and screenshots stored within your iPad's Photo Library can only be accessed using the native Photos App.

Given that the respective file browser UI’s are otherwise identical in appearance, it is easy to forget which file browser you are currently using (in-App, or Files) at any one time - but there is a visual indication that, when you’re “tuned in”, everything should become a little more obvious…

• When you are looking at the file browser within the Numbers App - the sidebar, title and buttons/links are coloured green. 

• For Pages - the sidebar, title and buttons/icons are orange.

• For Keynote - the sidebar, title and buttons/icons are Blue - with the entire page having a black background. 

• For the Files App, from which all files can be directly accessed, the title bar and sidebar all have black text; at top left, you will also see the Filestitle in black bold-text

This strategy in differentiating files by App is intended to avoid accidental deletion or changes to files that, ideally, should be stored with the App that is most appropriate for the document type.

You're very welcome. I'm delighted that I managed to offer some useful insight.