Every time a documents is opened, a message appears, saying that a font is missing, even if all text is deleted, an emthy document. This never stops, even after repeted open/close. 
This is a problem that appeared the first time after installing iOS7.
 I never had this problem on iOS6.
 Now a have hundreds of documents whit this problem.
What to do...? 
How to purge not used fonts from a document...?
iOS 7.1
It sounds like there is a template that references a font that Pages for some reason cannot access - perhaps due to some corrupt font cache or so. I'm guessing here, but sometimes my guesses are right.
What you can try to do is to remove Pages completely from your iPad (having backed up all your documents of course). The switch off the iPad. Start it again and then reinstall Pages.
To be honest, I have no idea if that will work, but it is what I would try.
Thank you for responding!
But, reinstalling Pages after, restarting, iPad, don't help.
Any missing font, should be replaced, by some existing font.
Or
The error message at opening a document should be suppressed.
Or
Maybe some invisibly characters/signs have the missing font,
And Pages can't changed font on something invisible.
If so, a setting, show invisible on/off, can solve the problem.
It must be a problem in Pages after iOS6
Fonts in document is missing, for ever, on Pages for iOS7
