[Ti] missing fonts in Keynote®

[Dr Trevor J. Hutley]

I cannot be 100% sure that 10.4.3 is to blame, BUT since the upgrade,  
every Keynote® presentation that I open says that it has a missing  
(Arial) font,

  eg ArialMS, Arial-BoldMS, Arial-BoldItalicMS, Arial-ItalicMS, etc.

The message is: add them to your Fonts folder, re-start Keynote®.

I would be happy to do that, but WHERE are they....????

Where do I find these fonts? I presume they were there before, but  
have now disappeared for some reason.
Where do I find them to re-load them?

Any ideas???   I have HUNDREDS of lectures/presentations which will  
be affected by this issue.


regards,  Trevor